Adventures in Hydro #2 - LP Aero/NFT mash-up - or - switching to HPA?

anon32470837 · February 20, 2019, 5:41am

It seems that if you do chlorine often enough - Ive been dosing almost every day - at hi enough doses - 4 to 6PPM - it will knock this algae back pretty good! I guess before, when I was doing the “sterile rez” thing, I wasnt doing it often enough or strong enough or both. Previously, I was only doing around 2-4 PPM every 3 or 4 days.

The last 12 hours or so, the PH at the nozzles has been exactly the same as the rez. The previous 18 hours or so, its only been up 0.1 at most. So, Im counting that as a knock down for at least a two count, but probably not a knock out.

Im very glad about that, but it has cost me fuzzies. I cant find any fuzzy hairs anywhere I can reach or see. Im going to pretend there are still some hiding in places I cant reach - which is maybe 80% of the chamber at this point.

The roots actually look pretty good - just not fuzzy.

I re-filled the rez with 6 gallons of RO, Mega Crop and MES at 2mM, and additional chlorine at 2PPM this time. There was still about 3 gallons in the system of the old mix at 5mM of MES, so the final concentration should be somewhere in the middle. Im too stoned to be sure Im doing the math correctly, so Im not going to give a number

We will see how this does.

Other than the cost, Im impressed with how well the MES has handled the upward PH pressure from the algae.

Northern_Loki · February 21, 2019, 5:50pm

How are things looking?

anon32470837 · February 22, 2019, 8:15am

Sorry, Im slowed down with kidney stones again. No big changes, but a new mystery.n I hope this makes sense - Im pretty stoned and in pain…

Reducing the MES and stopping chlorine additions every day, allowed the PH to increase in the tank and nozzles again. It went up to a 0.2 - 0.3 difference. Still, that was better than with no MES for sure.

Increasing the MES back to the 5mM range improved it - the PH rise dropped to 0.1 in the tank and another 0.1 at the nozzles.It seemed like the lack of added chlorine was keeping the MES from working as well as before. In other words, it appeared that the MES and the chlorine were each responsible for roughly half the PH rise.

BUT - then today, the rez has gone up from 5.7 to 5.9 over the last 24 hours, and for no reason I can figure out, the rez, tank and nozzles are all at the same PH = 5.9. I have NOT added any chlorine or MES, so Im stumped. Ive been feeling so bad the system has been running on LITFA.

The plant continues to look about the same. Some more foxtails have shown up over the least week or so. The oldest fan leaves on the lower parts of the plant look a little burned on the edges, but not bad. The middle aged leaves mostly look horrible - brown, burned and crispy. The youngest leaves look half decent, but there isnt much in the way of new growth. The roots continue to look like nice healthy hydro roots, but with almost no fuzzies to speak of. It does seem like they have finally stopped or at least slowed growth a lot.

Trich’s still look mostly milky with very few amber, so I still have a ways to go before harvest. Today is 58 days of 12/12. The range for this strain is 50-60 days, so it looks like Im going to run long rather than finish early.

I am expecting a good harvest as far as weight though. The main colas are significantly bigger than on my earlier grows. I have not seen any hermies or bannanas yet, but I would not be surprised if there were some after all this PH and other stress. Oddly to me, the top most buds pistils are still mostly white, but the lower ones and shorter colas are turning brown much sooner. There is an interesting purple tink showing on some of the buds. No clue if thats due to the PH issues or strain related.

MicroDoser · February 22, 2019, 12:01pm

I went to my grow shop the other day and had one of the usual ‘cryptic but ultimately very informative and spot on once I get a chance to think about it’ conversations with the owner.

We started talking about the plant, the symptoms, what I had done to try and find the cause of the leaf issue we both have. He was able to tell me the exact cross I have, and the name of the person who made it, and why, the year it was made, and the characteristics of my plant just because I told him it was psychosis and said the symptoms. Turns out I grow the psychosis cross made by Exodus (original psychosis was not made by them) which was destined for outdoors, very resistant to mould, grows strong, finishes early, and will continue to repair root damage well into flower and ensure a good yield in times of problems. He was even able to tell me that in normal times, the stalks of the leaves have a red tinge.

He does lectures at universities on plant science and is involved with international food production programs and is a consultant for a new plasma light in development.

He knows stuff…

I have yet to fully process what he said, and as usual, I need to google for a bit to figure it out properly.

Seems the P def we appear to have might be a lockout due to interaction with the CalMag or other additives (I now need to google what can cause P lockout). Either that or because of the highly tuned nature of our systems we need MUCH fewer nutrients in the solution and we are overloading the ionic transport system at the root surface and as it has preferences for other elements this manifests as a deficiency. Like the way alcoholics get a B12 deficiency he said.

And of course, it could still be a PH issue.

He did confirm signs that is indeed a P def are red leaf stalks and the red moves toward the main stalk, also in very early stages it shows as a slight leaf bend where a leaf looks like it will grow to the left then half way through looks as though it will grow to the right.

Anyway, I have things I can do to test deeper the cause and solution.

I will be keeping PPM levels well under 650, they just stopped eating at 700PPM. I will be in the 5.35-5.55 range at the nozzle more. I will be using a lot less CalMag now I know it is not a Ca or Mg def.

Once I have at a minimum reduced greatly the outward issues and they are growing well again, I will up the nute strength and play more with the PH.

anon32470837 · February 23, 2019, 4:58am

@SuperiorBuds Im looking forward to hearing more of your thoughts on what you posted. I have some comments on nute concentrations, but that will have to wait.

More later…

Oops! I was really stoned. That was supposed to say @MicroDoser - not @Superiorbuds !!

anon32470837 · February 23, 2019, 5:02am

MicroDoser:

Seems the P def we appear to have might be a lockout due to interaction with the CalMag or other additives (I now need to google what can cause P lockout). Either that or because of the highly tuned nature of our systems we need MUCH fewer nutrients in the solution and we are overloading the ionic transport system at the root surface and as it has preferences for other elements this manifests as a deficiency. Like the way alcoholics get a B12 deficiency he said.

And of course, it could still be a PH issue.

He did confirm signs that is indeed a P def are red leaf stalks and the red moves toward the main stalk, also in very early stages it shows as a slight leaf bend where a leaf looks like it will grow to the left then half way through looks as though it will grow to the right.

Anyway, I have things I can do to test deeper the cause and solution.

I will be keeping PPM levels well under 650, they just stopped eating at 700PPM. I will be in the 5.35-5.55 range at the nozzle more. I will be using a lot less CalMag now I know it is not a Ca or Mg def.

Once I have at a minimum reduced greatly the outward issues and they are growing well again, I will up the nute strength and play more with the PH.

Very interesting. It sure does seem like we are having similar issues - and as usual, there is no clear cut cause/effect or guaranteed solution! Thats the price we pay for playing with systems that have highly complex interactions with a great many unknown variables I guess

On the over strength nutes point, I thnik your NFT setup is probably subject to the same or at least similar issues we have with HPA - evaporation causing the nute strength to increase dramatically at the roots over what it is in the rez.

Here is how it can work with HPA. Take say a 1 cc volume of nutes that start at EC 1.0. If that 1cc is in a cube shape, it has a surface area of 8 sq cm. for evaporation to occur. However, if you break that same 1 cc of nutes into 50 micron droplets, you get 8 million of them. The total surface area is now 1600 sq cm. instead of 8 sq cm. So, the water in those droplets will evaporate 200 times faster when its broken up into tiny droplets.

If one of those droplets has time to evaporate enough to shrink in diameter from 50 uM to 25uM, the volume will decrease by a factor of 8 (Volume varies as the cube of the radius). That means the EC will go from 1.0 to 8.0 just due to the water evaporating from the droplet. Even small amounts of evaporation can make for large increases in EC between the time the droplet leaves the nozzle and the time it hits a root and gets absorbed.

I noticed early on that around EC 0.8 to 1.0 was about as high as I could go without tip burn.

This evaporation thing is also a factor in the Membrane Meniscus system I tried. Being able to use lower concentrations of nutes was one of the selling features. The whole point of that system is to provide the absolute minimum thickness of water to the roots as possible. In function, its like an NFT setup, but with the thinnest possible film of water on the roots at all times. Surface tension is all that causes the water to coat the roots rather than a fast flow or stream over the roots. That super thin film will also be subject to faster evaporation, though not to the extent spherical droplets are.

I suspect that any NFT system will also have some degree of additional evaporation going compared to other types of hydro. Mostly because of the far larger surface area of water exposed in the pipes and as it flows over the roots. It would be more pronounced where roots are more exposed to air and have thinner layers of water.

Anyway, the point is it makes sense to me that you might need lower EC levels than other types of hydro. How much lower I have no idea. Might not be significant or it could be a lot.

You might be able to check and see if there is any difference between the EC when the nutes leave your rez, before it hits the plants, and what it is right before it drains back to the rez? I suspect it will depend on your flow rate as well. Hi flow rates will probably eliminate any differences.

Ive been adding a ton of extra calmag to my system as well, so maybe I will cut back on that as long as I have the PH more or less under control now.

Its probably coincidental, but my burned leaf issues started when I switched to the Advanced Nutes. I mixed up the first batch at the recommended strength 0 which gave me an EC in the 1.6 range. I didnt lower it back down nearly fast enough. Of course, that was also the height of the algae/PH issues, so who knows how much of a factor that really was.

If you have any more thoughts on the leaf issues and the P def, Im all ears

anon32470837 · February 23, 2019, 5:08am

Almost forgot - the PH in the rez, tank, and nozzles are all still the same despite the much lower chlorine levels.

It seems to me that the more frequent addition of chlorine, at lower doses, is working much better than waiting 3 to 4 days between adding some at higher doses. I know it evaporates out of the system pretty quickly, but I didnt expect it to be that fast.

Im concerned that it may be building up in the tank because there is no where for it to evaporate to, but I have no good way to measure free or total chlorine. I have some strips but they suck. They dont read anything below about 20 PPM or more.

Im going to have to look for a better testing method.

MicroDoser · February 23, 2019, 12:28pm

Ding-Ding!

I think this is our winner, I was also doing this. It is the main thing I have cut down in the last few days. I was trying to chase what I thought was an Mg def by adding more Mg/CalMag and keeping the PH in a higher range.

It seems this may have been the exact opposite of what I needed to do. Last time I was there I really went to town with extra Ca and Mg with the idea that if this did not stop the deficiency, then it was 100% not a Ca or Mg def. It did not help, so it is 100% not Ca or Mg.

When I visited them and saw it had not helped, I emptied the old doser buckets of nutes and remixed some with hardly any Ca or Mg, refreshed the tank, and lowered the PPM to 350 and the PH to 5.4 and now they have started eating again.

Now (as I am in the last 2-3 weeks of flower anyway) I will slowly ramp up the feed, being careful to stay in the strength where they are still eating, and keep the PH low as I am sure they are full of lots of the stuff they can get at a higher PH…

I have been growing in this system for well over a decade, I feel certain that if there were issues with water evaporation causing nute strength increases I would have noticed by now, this moves my thoughts more towards the more recent changes which are RO, and too much CalMag.

The RO may have thrown out my base numbers, my tap water is at about 380PPM and PH 8.4. Getting rid of all that and keeping the same numbers would mean an overfeeding of up to 300PPM. I did drop my feed strength but maybe by not enough.

Here is the change in the last two weeks. The first image is bang on the crossover between weeks 4 and 5 (2019-2-5). In this image, you can see the slight leaf twist that is an early sign of a P def according to my shop guy.

The second is two weeks later (2019-2-20). Sorry about the low quality, the camera was on digital zoom and I did not notice.

Here is another shot to see the leaf damage. There are leaves as damaged as yours lower down, but I took these shots to check bud development and growth.

EDIT :

Found some better pictures to show leaf damage progress

2019-1-25

2019-02-05

anon32470837 · February 24, 2019, 6:10am

It sure looks like our leaf issues are very similar, although mine seems much worse than yours. Oddly, my older, lower leaves are much less damaged than the middle and upper leaves.

Now that Im not quite as stoned, I want to ask more about the comments that it could be the CalMag causing the problems. Did your guy happen to say what type of calmag was problematic or if it made a difference?

Your guy sounds like he is an honest to goodness real expert rather than the usual ‘stoner experts’ we often run into, but this is the first time Ive read anything about calmag causing issues like this. Have you found any other sources to back this up?

Im asking mainly because of one thing that occurred to me last night. I didnt see anything like this degree of problem until I switched brands of CalMag. I was using the GH CalMag which is the Calcium Nitrate and Magnesium Nitrate. The new one I have been using since this issue started, is Calcium Hydroxide and Magnesium Carbonate - no nitrates in either one.

Which type are you using @MicroDoser ?

Aside from the lack of nitrates, Im wondering if the added hydroxide or carbonates could be an issue? There are two differences btween this calmag and the GH calmag. The GH calmag increased EC, but didnt seem to change PH. The new CalMag is just the opposite - it lowers PH but doesnt change EC much at all. Obviously, the chemistry is very different.

Changing to the new non-nitrate calmag, plus switching to Advanced Nutes at higher concentrations were the two major changes I made at the time the leaf damage started to show up. Of course, the PH was wildly out of bounds on the hi side, so Im sure that was also a factor.

As usual - complex systems and changes with little concrete facts to go on.

MicroDoser · February 24, 2019, 11:36am

No. Like I say, he is rather cryptic and encourages me to find out things for myself but puts me on the right path. He knows his onions and I have had enough experience with him to know I do not need to double check what he says, although please feel free yourself as you do not have my years of being impressed by the subtle and cryptic guidance.

I don’t think a particular brand matters. He was talking about alcoholics and the way that even though they are taking in enough calories, they have thin arms from malnutrition. He particularly said about them having a B12 deficiency because the body prefers to uptake alcohol over B12.

In that context, asking the brand of alcohol or type of product with B12 does not matter, it is something that will happen no matter the brands.

He then went on to say that the CalMag products, and particularly the mono-element products I was buying are very very strong, even though the percentage number on the bottle might not be a very large number and this was a place to look.

As I say, I have now removed 90% of the Ca and Mg from my system (they are probably chock full of those elements now), I am now just giving them part A and part B (and some silicon) at a lower strength and they have started eating again at the rate I would expect for this stage in flower. Since the other day I have increased the food from 300-400PPM. 2 days ago they did not want to eat at 350PPM, now they are eating at 400PPM so good signs.

There are places I would investigate for more knowledge, like which particular elements can interfere with P uptake at the root surface and so on but for a solution, he seemed pretty product agnostic and it seemed the advice was mostly to just put less in.

To really know what is going on, and which changes are the ones responsible for the negative effects they need to be looked at in isolation. This is not really possible in a live system that is not set up like a scientific experiment.

So we must be like Dr House and treat for something and use that as a diagnostic tool with the logic that if the treatment works, we have found the problem.

I have treated for an Mg def and this made things worse. I will be going back to basics, lowering strengths, just putting in A+B, silicon, and maybe a bit of root stim/boost with minimal CalMag (I will probably go back to CalMag over mono bottles now I am sure this is the wrong area of investigation)

I will be starting at a level of CalMag where I should expect a deficiency over excess and I will only increase the CalMag if they show certain signs of Ca of Mg def.

I have tried a few, the mixed ones made my plants go dark green from the nitrogen but I think that was because I was putting too much in. I have not found a mixed CalMag without N in it so I went to the mono bottles with zero N in and my plants have still gone dark green from having the PH too high chasing a non-existant Mg def…

All this leads me back in a big circle to just putting less in and keeping my PH lower.

anon32470837 · February 25, 2019, 4:46am

Thats the story of my growing experiences for sure - make your best guess and see what happens.

My main question was not about brands but chemical composition. It may be 100% circumstantial, but my problem didnt start until I switched to this non-nitrate calmag.

Did you see the same symptoms when you were using the nitrate type calmag or only after switching to the elemental type?

This is the pre-mixed calmag I got that has no nitrogen. If this issue persists on the next grow, I will switch back to the nitrogen type. In the mean time, Im cutting back as you are.

I see they no longer have the quart size.

anon32470837 · February 25, 2019, 5:01am

Some up-dates.

I have been using the MES at 5mM and that plus the chlorine worked great as far as controlling the PH rise at the nozzles.

Dosing at 4 to 6PPM on the chlorine every day for several days seemed to really knock back the algae. That combined with the MES locked the PH in place so I had zero PH rise anywhere in the system. However, Im not wild about that much chlorine or MES, so I went back to adding about 2PPM of chlorine every two or three days. That combined with 2mM of MES still worked ok, but not as well, so I bumped back up to 5mM of MES.

After running about 10 gallons through that way, the PH difference went from 0.2 down to 0.1 and then to no rise at all, so on the last rez re-fill I didnt add any more MES, but I did add 2PPM of chlorine. After topping off the rez, I figure the new concentration of MES was around 2mM again. The last several days the system has been keeping to a 0.1 rise between the rez and nozzles. That seems to indicate that the algae is loosing strength even with the lower chlorine doses.

Im starting to see more amber trics, but still maybe 1% at most, so a few more days at least. Today is day 61 since 12/12 flip, so Im late for sure.

Roots still look like good hydro roots, but only a few fuzzies back in some corners - mostly on the mat on the floor.

I really hate this algae. I cant help but wonder how things would be looking if…

MicroDoser · February 25, 2019, 10:15am

Yes, nitrate type and individual elements.

anon32470837 · February 26, 2019, 2:04am

Ok, that kills my theory

anon32470837 · February 26, 2019, 4:16am

I just topped off the rez again without adding any more MES. Its very noticeable how effective the MES was previously as far as holding the PH and resisting changes. I should be down around 1mM now, and its taking far less PH Up or down to make changes in the PH.

I am very impressed with how well this stuff works. Thanks again to @Northern_Loki once again for all the research, detailed testing and educational posts!!!

Under some situations, I think this would make a viable option for someone with a nasty PH issue that needs short term handling. For long term, I still think it would be better to fix the source or what ever is causing the PH changes.

anon32470837 · February 28, 2019, 3:31am

I topped off the rez again last night with no added MES, but I did add more chlorine at 2PPM. The concentration of MES should now be well under 1mM. The PH is holding very nicely between the rez and nozzles - no more than 0.1 rise at most. It seems that adding chlorine every two days or so is doing the job - finally!

Im having second thoughts on these cheap UV lights. I found algae growing ON the end of one of the light tubes again yesterday. I also have algae growing in places on the circulating pump where no light can reach.

I dont understand why, but these are nice BIG strands - just like what you see in an aquarium that has too much light - except that I have been super careful about light leaks. The lid is off the rez at most two or three times a day when I check PH, EC etc, but never for long. The rest of the time is is sealed off really well. Plus the RO water, UV lights AND adding chlorine regularly. The tote is black, and the lid, and all the pipes are covered in foil, plus a large heavy blanket covers everything when Im not checking it, so I dont see light being a cause but???

Im not ready to buy night vision goggles just to check the rez PH!!

I am assuming there are spores still living in hidden cracks, and spaces in the pumps, on the lights, bulkheads, etc and they decide to grow back for what ever reason.

The trics are starting to turn amber and most of the pistels are turning brown and red now, so I think Im very close to cutting this baby down.

I think Im almost more excited about being able to nuke the algae than I am the harvest though…

I started soaking two Critical CBD fem seeds a couple of days ago. One is starting to show some root already. Im going to start them in mini dixie ‘hempy’ cups while I finish this grow and sterilize the system.

anon32470837 · March 2, 2019, 4:58am

I just realized there is another possible issue with these lights - heat.

I was thinking about these lights and wondering how efficient they were as far as how much energy is actually going into the UV part of the spectrum. Then it suddenly occurred to me that most of the energy that wasnt in the form of UV light, would be lost in the form of heat.

Oh crap. Ive been running 26 watts of heater in my rez! I checked the water temp and sure enough the rez is running about 4-5 deg F above room temp. Thats not a huge issue now while the temps are low, but later this spring it could become a problem.

The plants continue to mature with more amber trics showing up every day, but it still has a few more days at least.

Im a little worried about some spots on the roots that are turning brown. The PH is NOT going up at all between the rez and nozzles, so the algae should be minimal.This is all happening in the same places where the bleach treatment a while back burned the roots, so maybe it is some rot from that? Some USB pics looks very similar to the original brown crud. This is all guess work though.

I started two Critical CBD seeds a couple of days ago. They are now in baby dixie cup hempy’s. I shuld have started them a couple of weeks ago.

anon32470837 · March 6, 2019, 4:20am

I started two seeds last week. One has done great and the other one is going really sloooowly. The good one is already over 2" tall in the dixie cup but the second one still has not come up from the perlite and its roots doesnt seem to be growing well at all. I put the slow one back in a damp paper towel to see if that will help. I may dump the slow one if it doesnt catch up by the time Im ready to put them in the system. I really wanted to do two this time, but oh well.

On other news - its HARVEST TIME!!! I could wait another several days but I think this is close enough. As usual with these plants, the signs are mixed. There are still some white hairs left, but not many. Almost all the trics are cloudy, but in some laces there are still a fair number of clear ones and no amber ones. In other places, ots all cloudy with lots of amber. There are also some spots with purple in the trics.

I dont want much couch lock with this harvest, so Im going to cut it down. Plus, I need to get the next batch going before it starts to get too warm later this spring.

Ive been at it for almost an hour, so break time. Ive mostly filled one cookie sheet with 510 gms of wet bud.

Im going to go out on a limb here and guess what my total harvest is going to be. Judging by my non-calibrated mark one eyeball, Id say Im about 15% of the way through. If Im right, that means about 3400 gms wet. If this follows my last two grows, dry weight will fall between 22% and 26% for somewhere between 750 and 880 gms.

Im thinking my eyeball may be off a tad or two because thats a lot more than either of my previous grows. My soil grow with 4 indica type plants netted 426gm dry and my first hydro grow with three clones netted 559 gms. Both in the same tent with the same lights and mostly the same nutes.

Im having trouble believing that will actually be my final weight after all the algae, and PH issues, and especially how crappy the leaves have looked the last several weeks.

We will see…

To be honest, Im more interested in the weight and condition of the root ball

Some pre-harvest pics…

anon32470837 · March 6, 2019, 5:24am

Well crap. It looks like I have a bunch of seed pods on the lower parts of some of the largest colas. So far it looks like its only on the three largest ones, but the lower 1/3 to maybe 1/2 of the buds sure look like seed pods to me. The upper portion look fine other than foxtails on many of them.

Im going to set those aside for now and weight them separately.

This is one of the lower buds from one of the largest colas. Looks like all seed pods to me. They are also very light weight compared to other normal looking buds. I havent seen any nanners, but they are easy to miss. Are there always white hairs growing out of seed pods too?

MicroDoser · March 6, 2019, 6:02pm

You may be surprised. Even a clapped out old Ferarri that runs with problems will beat a new tiny ‘city runabout’ type car. I have found the difference between a hydro grow with one serious issue during flower and a hydro grow with none to be around 200%. It is not beyond imagining that there would be a similar difference between a soil grow and HPA which is, after all, a rather advanced highly tuned system. The increase from soil to first hydro grow seems right, being about a 30% jump. That is just what you get for free with hydro. A few more hydro runs and you could add another 30% to that with ease. With the ridiculous amount of aeration you have with HPA though, 850g or thereabouts for a first run seems right to me. I would imagine you get a lot more ‘free’ yield with an HPA system.

Of course, this does mean HPA has a lot of headroom to explore and I would not be surprised if after a few runs you were getting 1000g+ from the same space, with the same lights. Small increases in bud size combined with increases in bud density and node shortening can have great effects on yield.

If we start at 420g (why not) and assume your buds are 20% denser, and each bud is 30% wider, 25% longer (not too extreme). The bud area will increase by 69% (4201.69=709) and with the 25% extra length, this will increase (7091.25=887). 20% denser buds will mean 887*1.2=1064g.

These are not beyond the differences you could see going from soil to a highly sophisticated system. (yes I know soil itself is a highly sophisticated system but that is another discussion )

Fingers crossed you have already got some of those gains.

It’s the first time I have seen that. Normally the hairs die off when they get fertilised.

Shame about the seeds but it isn’t a complete loss, you could get the seeds out (or not) then do a butane blast on the remaining bud and get some oil.

Looking forward to seeing the first data point in the HPA log. To me, you looked to have a great root ball.

In other news, IT’S HARVEST TIME! for me too. No pictures of the whole thing before chopping but here are some bud shots. I also had crappy leaves but it seems this is not a block to a decent yield in our systems. To my mind, this is another sign of oversupply of some nutrients causing the problem lockout. Actual deficiencies give lower yields. (bolded to be noticed by the stoned or otherwise medicated )

Here are the crappy leaves

and here are some whole plants to get an idea of the size they get to. The one on the left had to have about 3 ounces chopped off so I didn’t rip buds through the support fencing. This was a short one, just 9.5 weeks from the cutting going into the system to being cut down. For some reason, they just finished really early.

As you can see, it is a short dense plant that needs no topping because it branches like mad.