Backyard Aquaponics
A place to discuss aquaponics

Hello everyone. First time trying out aquaponics here. I have a 55 gallon tote set up on a constant flow system. I'm using blue tilapia fingerings and the tank has been set up for around 2 months maybe a little longer. I'm growing straberries which seam to be growing good. Picked my first 2 today! I'm just worried about the leaves. I attached 2 pictures of what they look like. Could this be a fungus or a deficiency? I was thinking deficiency but didn't want to add anything that's not needed.
Ph 6.0
Ammonia/nitrite 0
Nitrate 80
Water temp 76
Temp on top of leaves 82. It's in the garage so it does go down to the 50's at night once the light turns off.
Once the leaves started changing colors I noticed the nitrates starting to climb. I know I need to get them down. Could this be my entire problem?
Thanks for any advice!

Hi and welcome to the forum

I'm not sure about the spotting on the leaves but the yellowing between the veins is probably because of an iron deficiency.

I noticed your pH is at 6.0. That's as low as the API test kit will read so if that's what you're using to test your pH, the pH could be even lower than it looks and you need to raise the pH. Try to bring it into the 6.2 to 6.8 area. Getting too low could cause trouble with nitrification among other things.

Looks like a nutrient deficiency. I'm still learning but if older leaves are affected, I'd guess a potassium deficiency. If only new leaves, then maybe iron.

You'll need to increase pH soon. If you add some potassium bicarbonate and lime it will up pH and solve the deficiency. Add small amounts 1/4 teaspoon at a time and test frequently.

If you alternate between lime and potassium bicarbonate for pH comtrol, you'll prevent potassium and calcium deficiencies.

Could I use baking soda to boost the ph? It's sodium not potassium bicarbonate. I've used it for my tropical fish before. I'm on a well and my ph is right around 5.5.

Could I use baking soda to boost the ph? It's sodium not potassium bicarbonate.

not ideal since Sodium (Na) tends to bond with CL etc to make salt.
Strawberries don't like salt, and it will accumulate.

Potassium and Calcium will get used by the system.

Stay with the advice above.
Garden/agriculture lime is very common at garden centres etc.
May have to look a bit harder for potassium bicarbonate but many home brewing suppliers carry it.
It is also widely used in the wine industry.

Thanks! I'll see if I can find the suggestions then post back with the results.

Would this be aquaponics/fish safe?
https://www.amazon.com/gp/aw/d/B01M0QOG ... icarbonate

Pottasium Metabisulphite K2S2O5 is not KHCO3.
That is a bit of BS labelling from Amazon !!

keep looking for Potassium Bicarbonate - it is pretty common.
even health supplements people use it but it is very expensive to buy that way.


[edit] you could even go Potassium Carbonate even...has better pricing on amazon.
https://www.amazon.com/Potassium-Carbon ... icarbonate

Potassium Bicarbonate in bulk is usually around $30 for 3-5kg.
But smaller quantities on internet often much more /kg.

This also seems to be OK source for potassium bicarb (although I haven't bought from here):
https://www.amazon.com/Home-Brew-Ohio-3N-PD8E-MWY4-Bicarbonate/dp/B0064GZPU4/ref=sr_1_1?ie=UTF8&qid=1488510320&sr=8-1&keywords=potassium+bicarbonate

I'm going to start with the lime since I can get it quicker than ordering online. I'll order the other stuff this week. Would this one be fish safe?

That should be fish safe. As with any lime, it will increase pH. Add in small amounts and measure often.

It's dolomite lime, so you'll get some Magnesium too. If you can't get Potassium carbonate or bicarbonate, Potassium hydroxide will bring your pH up and add Potassium. You'll only need very small amounts in your small system, and have to be careful handling it, as it is a very strong alkali, and will remove your fingerprints quite easily. Don't add it directly to the FT.

Thanks! I just added 1/4 teaspoon. Ph is at 6 on my api test and 5 on my old expired tetra test kit.

Dolomite lime will only move the pH quite slowly, builder's lime, Ca(OH)2, will be much more drastic.