Good call, I suspect you will find a constantly rising level of copper but if you do tank changes often enough it may be fine.
2 Likes
I agree. It will be interesting to see how long I can go before the copper starts to show up. A big unknown is how long it takes the copper to build up to dangerous levels in the plant.
So, its been about 10 hours and no sign of copper in the rez yet. Also no sign the roots are effected by the copper.
Here is the copper wire last night.
And this morning - 10 hours later.
3 Likes
Another 24 hours and still no sign of copper in the rez water. I did the test just before adding another 3 gals of water to the rez. These plants are now drinking around 3 gallons a day out of my roughly 14 gal rez. Thats a hi %, so its goign to take longer for any copper to show IF the plants are taking it up as they drink. Another question to add to the list.
BUT - also no sign the roots are being slowed down by the copper wire.
1 Like
Well, another 12 hours and the roots still dont seem at all worried about the copper 
Im going to leave it in there as long as it takes to see if there is any result. I wont test for copper again for a few days. At the rate Im having to add water and nutes to top off the rez, i dont think build up is going to be any problem at all, but I will test every so often anyway.
1 Like
Fascinating stuff, Larry. No darkening of the roots in direct contact with the copper wire?
1 Like
No change of color that I can tell so far. Also, they dont seem to be slowed down much at all.
Here are the last two days worth of shots - up to tonight.
There is certainly no dramatic reaction to the copper that I can see.
I decided to try a slightly different layout of the copper to keep the roots from going around the back side of the wire. I also put a coule of short pieces directly on some roots at the ends - to see if there is any reaction.
So far, Im thinking this copper stops roots thing is an old wives tail, but I want to test it a bit longer.
4 Likes
Well whichever way it works out this is the only way we will ever know what will happen, thank you for posting this experiment 
3 Likes
Really cool experiment. Appreciate you taking the time to test this out. All’s well that ends well! I’m hoping this ends well!
1 Like
what ppm of nutrient solution are you running and what brand?
1 Like
Im using Mega Crop, plus some cal mag and Hydro Guard. My meter is broken and the new one has not arrived yet, so Im kind of guessing on the numbers, but they were as follows:
tap water = EC 210 = 105 ppm
Cal Mag = EC 160 = 80 ppm
Mega Crop = EC 1036 = 518ppm
total = EC 1406 = 703ppm
1 Like
I would like to see the effects of 1500 ppm salt based hydroponic ferts on copper. As soon as I get to 1500ppms I will take some out and put copper in it like I said I was gonna do a year ago but never did.
1 Like
Are you looking to see the effect on the copper itself or are you looking to see the effects on a plant sharing the solution? For the first, Larry did try an interesting test with copper metal in solution (a bit earlier in the thread). He noticed what appears to be additional free copper in the solution.
1 Like
I want to know what happens If i put a copper coil in my Rez to run chilled water through.
What the effects of the copper will be on the solution and plants.
2 Likes
That would be interesting as well.
Larry’s testing has shown that copper certainly does appear to dissolve into the nutrient solution at a PH less than 7.0. The free non-complexed copper was increased in a rather dramatic fashion for the case where there was a relatively large amount of copper as compared to the volume of solution (kind-of an accelerated testing). This was in-vitro (outside of the system).
His latest tests do not appear conclusive as of yet with the possibility that there is very little extra copper added to the overall volume of the solution, the extra copper was chelated/complexed within the solution, or the extra copper was absorbed by the plants. Or, a combination of those. Perhaps as his test continues, any change will become more apparent.
With a copper coil, that would probably have a significantly larger surface area and may have a more pronounced effect. The PH will be the main contributor to copper dissolving into solution, I believe. With an increased EC, there may be more CU complexes created or slightly lowered solubility. https://academic.oup.com/chemse/article/31/7/689/278058
Cu2+ is free copper where the remainder of copper complexes. The test kit Larry has measures the free copper in solution.
By the way, I’ve been putting together something similar with a cooling coil in the reservoir but am using a stainless steel “wort” chilling coil for the same reason, not certain of the long term effect. The more experiments everyone tries, the better I would think. Stainless is much more expensive than copper and, perhaps, using a copper heat exchanger coil to chill a solution won’t have a significant effect on the health of the system. Or maybe the copper will end up in the plant. Don’t know, claims go both ways. Would be interested in seeing the results of your test.
3 Likes
hi All
We don’t really have much input into copper in hydroponic systems. So I can’t say if the system you are talking about will work or cause problems. Good luck though!
2 Likes
Two questions about that.
-
I thought all nutes were more or less salt based once you get down to the actual usable chemicals in solution?
-
1500 PPM = 3000 EC. Thats seems really hi to me - at least I havent seen anyone else talking about levels that hi. That would be more than 3 times the recommended dosage for Mega Crop for example. Are there other nutes that use that hi a feeding range?
I have read a few reports on other boards about copper cooling coils corroding, and turning green. So far, I have not found any reports of plants being damaged from over doses of copper or showing any symptoms of copper poisoning. I guess people tend to freak out when their copper coils turn bright green and the stuff flakes off into the rez 
I am pretty sure that the coils turning green is more than likely due to some form of electrolysis or galvanic corrosion rather than a direct chemical reaction to the nutes in the rez. That could occur if there were two different metals in the solution (the copper coil, plus a piece of aluminum, or steel, or tin, etc) - causing the battery effect. Or it could be due to stay electrical currents from poor wiring, bad grounds, leaking insulation or seals in pumps, etc. It only takes micro volts to cause that type of corrosion.
My copper wire has shown zero signs of green. It is just doing the normal oxidizing which is more a brownish color as you can see in all the pics.
It will be interesting to see your test results. I think more people might be wanting to use copper coils to cool a rez (for money and easy of working) than will be wanting to stop roots. If my results keep going like they are, then there is no point in using copper against roots. Its been another 24 hours and still no real sign the roots have any kind of problem with the copper.
I moved one of the small pieces of copper on the left side onto some roots that were whiter in color. It may be easier to see if they brown up.
Here is the most recent pics from this morning and tonight.
1 Like
Of course. Here is a quote from G.H website. “GENERALLY, nutrient strength should run between 800 to 1500 parts per million (ppm). Your exact ppm requirements will depend on your circumstances and style of growing.”
I believe @LED_Seedz has already commented about the negative effects of copper in a res.
1 Like
Thanks! I learn something new almost every time you post something
To be honest, I took that as more of an anecdotal comment that was more about the damage to the copper coils, and not really a report of damage to the plants. His mention ‘off gassing’ tells me there had to be significant stray voltage in the system - which would cause a lot of electrolysis, which will generate a lot of H2 and O2 gas. Copper wont off gas unless its in a very concentrated acid bath - way beyond what we have in our rez’s.
I’ll have to see if I can find some old pics I have of some experiments I did a few years back with that exact subject. It was in relation to safe disposal lythium batteries, but the effects are the same.
2 Likes
I noticed the terminology also and simply took it as meaning “dissolve”/contribute copper to solution. I would be a bit nervous if I saw electrolysis or active decomposition occurring where it wasn’t supposed to 
2 Likes
I still had them! These were taken by me several years ago. I wont go into why - its along story about how to safely discharge lithium batteries before disposal.
Anyway, this is just some tap water with an additional tbl spoon of salt added in a quart jar. I then applied 12 volts to the wires. One wire was bare copper, the other wire was tinned copper. Some of these also had a small piece of aluminum attached to one or the other lead.
The whole point of the experiment was to demonstrate how fast metals will corrode away to nothing when you have even a small current flowing in a salt solution.
The water in the jar started out perfectly clear. These pics were taken 2 minutes after applying power. Remember, this was only 12 volts and the current was only 0.30 amps.
Electrolysis and galvanic corrosion can act very fast and do amazing amounts of damage in an amazingly short time. Several grams of aluminum and copper were completely gone in just a few minutes at that low a voltage and current. Even very very very small voltage leaks can do a lot of damage over time.
3 Likes