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I have a system that is only 2 months old. My plants are turning yellow. What nutriance can I add to give the lettuce and basil a boost but not hurt the tilapia?

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Thanks Nate, much appreciated.

Cool, Thanks!

Nate Storey said:

You're looking for interveinal chlorosis- yellowing of leaves between the veins, especially on old growth leaves.  Iron is mobile within the plant, so new leaves won't always show chlorosis, look on older leaves.

I started cycling about 4 weeks ago added some seedlings to each of (5) 40 gallon GB.  The goldfish were added to the system about 3 weeks ago and koi about 2 weeks ago.

I'm having similar problem with yellowing .... though some plants seem ok while others are showing signs of yellowing.  The 'ok' plants are the radish, broccoli, peas, swiss chard, and sugar snap peas.  The yellowing plants are cherry tomato, campari tomato, cucumber, green beans, and silver queen corn.  The corn is just pale green on the newer leaves while the other plants are more yellow on the newer leaves.

The water ph is 7.5 and temp is being regulated between 70F to 74F.  The fish tank water is filtered and there is algae growing on the bottom and sides although the water is pretty clear and easy to see through.  The air pump is an AP 20 Danner and on all the time.

Ammonia is consistently zero when checked in the morning.  The 5 comet goldfish and (3) 5" koi are being fed 3 maybe 4 times a day (flakes and koi pellets).  I have been adding ammonia to each bed to get the level to .50 ppm but it seems to go back to zero in about 5 to 6 hours.

Nitrates look like they are about 20 ppm but the chart color for 10 and 20 are really close.  It's not over 20 though.

I haven't checked nitrites since I have nitrates but I will check in the morning.

I have been adding kelp meal tea which has 1-0-2 and today I added a few tablespoons of worm castings to each bed.

I was wondering if fish fertilizer would be a bad idea to add in small amounts.

Looking for Sprint 330, I see Amazon has 5 lbs for about 49 bucks.  It's hard to find anywhere else.


Here is a picture of the Nitrite test:

Looks like 2 ppm to me

Amazon also sells "Maxicrop + Iron".... personally, I'd buy that... and stop using all the other stuff... or any other stuff...


Your "nitrites" might be being affected by the "kelp meal" ... and your algae is symptomatic of your pH and "fertiliser" additions... (basically... you're just feeding the algae)


Add more aeration, if possible... and pump continuously for a day or two... covering the tank...

Your algae, and nitrites... should disappear...


P.S... if you have fish in the system.... don't feed them for a couple of days...

If you have measurable nitrates, you do not need to be adding ammonia, you have enough nitrogen and that is not the cause of your leaves yellowing.

The recommendation to switch to maxicrop plus Iron is a good one.  Or since You have already been adding the kelp meal, you could simply stop adding everything, and get a bit of chelated iron to add instead which should hopefully take care of the yellowing since with you high pH you are probably seeing Iron deficiency.

I really appreciate the help.  Thanks :D

I ordered the Maxicrop with iron but in the mean time, I found another chelated iron plant supplement for the immediate problem.  It's a product called Flourish.

I stopped added ammonia and will keep an eye on the nitrites now.

My plants are looking great.  The iron has worked.  We ate our first head of lettuce. It was outstanding, maybe I am biased.

Great news, good to hear it.

Benicia Bendele said:

My plants are looking great.  The iron has worked.  We ate our first head of lettuce. It was outstanding, maybe I am biased.

My plants look great now. However, my ph jumped to 9 would the iron the the cause of that?

Benicia Bendele said:

Thanks for the info, I will start the process tomorrow.  When you say look at the tissue what exactly am I looking at the roots?  What am I looking for discolorazation?

Nate Storey said:

Hi Jon, I guess I didn't read that carefully.  You want to dose on water volume, not growbed volume.  Dosage will be highly variable depending on the algae conc. of the system, so unless you have a lot of fancy equipment that I can't afford, the best way to dose is hit a baseline and then watch your plants very carefully and respond to nutrient deficiencies.  Or, if you're commercial, do tissue analysis and respond.  That dosage rate is based on my experience.  It should help hit baseline on a per gallon basis and then allow you to drop your rate and respond as plants begin to show deficiency.  You don't want to over dose, but more is better than less when it comes to iron.  In populations with high populations of algae, your iron will dissapear fast, and much of it will become plant unavailable in the process of algal assim. and decomp.

While you initially dose on a per gallon basis, down the road as you expand your plant production you'll want to switch over to a steady biomass basis for dosing- again that depends on watching your plants, tissue analysis, or water testing.  Water testing is not great though, I'm not sure most testers can separate ferrous, ferric and amino-bound (chelated) iron in tests, so the best way to monitor is 1) tissue analysis, 2) visual deficiency monitoring, and 3) water testing. . .   Any way, I'm commercial so I choose to stay ahead of the curve and dose at a steady rate that works for me.

No, iron is not caustic plus there is only 2% in the Maxicrop.  What are you using for grow media and how many liters or gallons of media are you using?

A PH of 9 doesn't sound right... I would make sure the test vile was clean and retake the test.

What is the source of your water?

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