Google is awesome
6 Likes
All nutrients come with a set NPK. A plant may take more % of N during veg period changing the NPK ratio in your rez. When you top up the rez with new nutrients the P and K that was left over in the old mixture remains so when you add the new mix the P and K will be a higher % and can cause toxicity.
Thatās why weekly rez changes are recommended so you know exactly what levels of each nutrient element your plants are being fed.
5 Likes
Best graphic I have seen so far. thx.
Hmmm still thinking about the calMag issue.
5.5 - 5.8? What medium are you using for your grows? I did read if you have a magnesium issue then it can be cause by ph and if you add magnesium without adjusting the ph will not help. And in hydro magnesium gets absorbed best at 6.0 to 6.5.
2 Likes
Spray them with epsom salt solution, if they turn green after a few hours the next day the latest - itās Mg def.
Mg is highly mobile and easy absorbed thru the leafs, so the plant can correct that easy with a folia feed.
And yes pH lockouts or any type of lockout, will stop the roots uptake of the locked nutrient.
A res change is the quickest way, to fix any of these issues and then keep it running till it happens again.
I do drip feeding in pots of clay pepples like Hydroton, the cheapest coated expanded clay pepple for floor insulation I could find.
5 Likes
Without pictures itās impossible to advise properly. Iāve seen people stress out thinking they had a problem and there has been absolutely nothing at all wrong with their plants. Over thinking and over nurturing can cause a lot of unnecessary problems.
The best way to fix any problem in dwc is to dump the rez and start again. The plants will thank you for it 
4 Likes
never done foliar feeding. I will do it tomorrow.
how much grams of epsom salts per liter?
Also what ph of the water?
Btw I have plenty stuff of epsom salts and of this:
āYaraTera CALCINIT (15.5% N + 26.3% CaO) is a fully water soluble nitrogen and calcium fertiliser. It is a free flowing, fine granular or prilled material which dissolves quickly in water without any residues.ā
But I dont know how much epsom salts and calcinit I should add to the lucas formula of ghe. So I didnāt use it until now.
Are some people on the board here doing their own calmag or using lucas formula?
1 Like
Are you sure there is a problem that needs to be fixed?
If youāve made it to week 3 of flower and the only sign of deficiency is a couple lower leaves yellowing, it might be better to just continue doing what youāve been doing.
6 Likes
Canāt remember the ratio of epsom salt pr Liter
I recall I add about a tea spoon full for a liter, but google it as im not at all sure.
3 Likes
Half teaspoon per gallon 
4 Likes
I go full cycle with only one 75l rez change at flower timeā¦ but would be hesitant to go much longer than the 6-8 weeks flower time takesā¦ It does depend a LOT on how large the rez isā¦ commercial NFT greenhouses often have multi thousand litre rezās that are only changed out every three of four monthsā¦ but I would expect the solution woudl be getting pretty funky by that pointā¦
imho if left too long you just end up with too much old root material floating around asking to go bad, and as @ReikoX has indicated, it gets increasingly difficult to know your actual nutrient levels from saltsā¦ Yellowing could be nutrients, but the cause of this might be the actual nutrient levels, or it might be salt levels interfering with the osmotic potential of of the plant cell walls and thereby restricting both water and nutrient uptakeā¦ So there might be sufficient nutes, but the plant canāt access them.
One approach I have read about but not tried to extending the rez change outs is to add some activated charcoal to the resā¦ The method I read used the charcoal as a floating top mat on the rez, but I donāt see any reason why you couldnāt put the charcoal in a small āpillowā of some kind. This will also apparently filter out most organic material in the rezā¦
I have a litre of 98% sulphuric acid that I water down with distilled water to raise PH, and I have 1kg or granular Potassium hydroxide I use to lower itā¦ I got sick of buying ph up and down and these cost me hardly anything and will last me foreverā¦
100% thisā¦ MOST issues you will see are about too much love, being lazy isnāt just easier, itās often a better growing strategy 
6 Likes
when foliar feeding, can I overfeed? E.g. If I would feed the epsom salts three days in a row??? Something adverse could happen?
2 Likes
You sure can big time and itās real easy to burn them this way. Just go easy on nute strength, you will get a pretty rapid response from foliar feeding so it may pay to be sparing on how often you use it to start with just to see what the plant does, any burn will show up nearly immediately.
Epsom Salts, i.e Magnesium Sulphate is much better absorbed through foliar feeding than via roots, particularly where elevated levels of potassium can interfere with itās uptake via root/soil applicationā¦ It plays an important role in the production of chlorophyll so one of the symptoms of deficiency is leaf sclerosisā¦ i.e yellowingā¦ When I apply it with via foliar feed I apply it at 10 day intervals at a strength of 3% w/v i.e 1% w/v is equal to 1 kg/100L.
4 Likes
A larger res would allow you to go longer between res changes. Personally I can barely fathom that large a res.
3 Likes
what you mean āISā? 
1 Like
with a big res the imbalances of nutrient build up get blanced out by the volume?
When you keep your ph always between 5.5 and 5.8, what nutrients you use? Are you foliar feeding epsom salts also?
What nutrients do you use and what medium? What range you keep the ph? Are you always foliar feeding at 10 day intervals?
Typically I use Maxi Bloom @ 1.94 grams per liter in a RDWC system, but I also use the same mix with coco/perlite.
I also add Fulvic Acid and a kelp tri-mix of 3 different varieties of kelp as well as mychoriza. In veg I add some calcium nitrate at .8 grams per liter give or take depending on what the plant does. In my current grow however I am using a cheap ass 2 part dry powder hydro mix I got from the hardware store for $8 after first running itās ratio of ingredients through Hydrobuddy and discovering it has everything the plant needed. Plants havenāt invented a need for mega flashy and expensive nutrients, self interested commercial sharks have.
Personally I prefer being able to dish out the nitrogen separate so I can tweak the amounts, same goes for the rest of the nutrientsā¦ Ph baseline is about 5.8, but when adjusting I typically drop it to 5.6 and then let it creep up to 6.2ā¦ but I am a long way from obsessive about it 
some plants seem to be able to take stupid variations in Phā¦ some seem a LOT more sensitive.
Hydrobuddy link
Noā¦ rarely really and mostly if/when I have an issue that is being difficult to remedy or on the very rare occasion root rot turns up and think might be recoverableā¦ which is hardly ever. I basically use foliar feeds as life support lol. If you have the motivation you can get significant growth improvement via a foliar feeding regimen, but you are mostly limited to veg and maybe a few weeks into flowerā¦ after that it gets a little risky rot wise to be wetting the flowersā¦ at least in the climate here.
5 Likes
Means you were correct 1st guess
2 Likes
GHE basic 3part - I donāt use much epsom at all, some strains like a bit extra sure.
I folia feed with biobizz fish-mix as the only other thing I use, beside GHE Gro, micro and bloom.
You should take a look at my thread āThe LED hack shack and other tall talesā
Itās faily long and a lot of me building shit, but there is also a bunch about my hydro.
Pictures and notes on Ec and pH, on the given time of flowering.
7 Likes