Backyard Aquaponics
A place to discuss aquaponics

I started my IBC system 7 weeks ago with 150 gallons water, 1 grow bed (with river rocks that I washed & tested with vinegar - no bubbles), 7 goldfish (that are about 3-4 inches now) and some seeds. Its a continuous flood system (no flood & drain), but with the water level about 1 inch under the media.

About a 3 weeks later, I added 30 tilapia fingerlings (that are about 2 inches now). About 2 weeks later, I added some red earthworms.

About 4 times, I've added Maxicrop Liquid Seaweed plus Iron.

About 3 weeks ago, my system had full cycled after the Ammonia, Nitrites and Nitrates all spiked and then returned to zero. Which is where they are at today.

However, with pH, the Low pH test has stayed at 7.6 since the beginning. The High pH test has read 7.4 most of the time, but today, I think it's reading 8.0. I honestly can't tell, so I've included a picture & maybe you can tell me.

The fish seem healthy (no deaths & they are growing & eating well) but the plants have not been growing well.

I've included pictures of sweet peas. They are growing pods, but the leaves turned yellow and now are turning black and dying. Same with my lettuce. It grows to about 3 inches, then begins to wither and die.

I went to a Hydroponic store near by. They also have an aquaponics system set up there, but don't know much about aquaponics. They gave me some free samples from MicrobeLife Hydroponics, which are labeled "Safe for Aquaponics" (see their website here: https://www.microbelifehydro.com/produc ... ample-kit/) but they didn't know if it would help or hurt.

I have used all 4 samples of the MicrobeLife & followed label instruction, but it turned my water green (see picture) and my plants are not getting better.

My assumption is that my pH is too high, causing my plants to not be able to absorb the nutrients, but how do I safely bring down the pH, if that is the case. And how to I clean up my water now? Do I need to slowly replace it (like by 25% a day) or something? I'm also wondering if I need to add iron (but the Maxicrop has it in it, so dont' want to over do that).

Any help on any of these issues/questions is much appreciated.

Thanks!
Dave (aka Aquaponics in Georgia)

never buy "hydroponic" products again.

the green water will go away by itself if you are patient, otherwise battle your heart out with covers and UV clarifiers.

to bring PH down, buy some hydrochloric acid and use very sparringly (make sure you read the ratios on the bottle) - dont go back to the hydro store! dont buy PH down!

Thanks for the feedback. I have ordered some hydrochloric acid and it should arrive today. Do I put it in directly (as directed on the bottle) or mix it into a separate container of water to add/or switch out? Any guidelines on how to lower the pH safely. I've read you have to do it slowly, but not sure how exactly.

Also, do you think this is my only issue with the plants - that the pH is too high? Do they need iron or anything else do you think?

Definitely mix in a separate container. Make only a small adjustment each day. Safest way is to adjust topup water to pH of 6-6.5 each time you add water.

HERE'S AN UPDATE:

I put some hydrochloric acid in my top-up water. The pH was 6.2. My tank was 9.1. I added 2 quarts several times over several days. The pH only came down to 8.9 but then kept rebounding to 9.1 or so every day. I think it is the green MicrobeLife additives.

I decided to remove my fish and change out ALL of the water to get rid of the green MicrobeLife additives & lower the pH. I know that's not recommended, but I went for it (spoiler alert: none of my fish have died).

So, I removed most of the tank water & put some in a separate tank. I caught all of my 30 fish (mostly 1-4 inches long at this point) and put them in the separate tank with their original water (still at 9.1 pH).

I replaced all the water in my tank. I rinsed out my grow bed. I removed the dead plants (there are still some cucumbers & basil growing).

I added a declorinator to the new water in the tank & ran the system overnight. The next day, the tank was at 7.7 pH. I slowly acclimated my fish to the new tank water by doing slow changes to the tank they were in, and ultimately put my fish back in the big tank. (They are a robust crew since none of them have died through this ordeal.)

Today, my tank was at 7.6 pH this morning, then by noon (in the sun) it was 8.6 pH. I've read that pH is supposed to go DOWN when the water heats up, but my is totally the opposite. It's lower in the mornings, but gets higher as it warms up in the day.

So...I started another cycle of adding 2 quarts from my top-up water (which is at 4.1 right now) and after adding 4 quarts, my tank is still at 8.6 pH. I plan to keep doing this daily until the pH reaches 7 but it seems to be a losing battle.

Note: I assume that it is not my media, because it is smooth river rocks and they didn't bubble when I put them in vinegar when I started my tank, but I could be wrong. I'm assuming it is still the green MicrobeLife additives as the green water color has come back (probably from remains in the growbed) and my water is green again.

The good news: My fish seem very happy and hungry at each feeding and I have seen the green color come back in my plants and they are growing again.

Any other great ideas to lower the pH and keep it down? Thanks!

sometimes people just have to fight a losing battle or wait out a high PH from new media, etc. even if it seems like it is inert, my PH always used to be around 8.5 when my system first started.
I did combat it with Hydrochloric, but i dumped it straight into the tank every so often, just do small amounts too.
if you arent leaving your top up water for a few days before adding to the system, you might as well put the hydrochloric straight into the tank as the PH has to stablise before adding it to the system - which is probably why you are seeing such large bounces. (you must HOLD the top up water at X PH for more than 1 day for it to really be X PH.)

if your fish are surviving and you are patient, just wait it out.
otherwise i would just dump the right amount of acid into the system to bring it down by about 0.2 - 0.3 (0.1 is safer, but slower) per day- it will always bounce back up, but after a few weeks of doing that you might find the PH starts staying down a bit lower.

but dont bring it all the way down to 7.0, because when the acidification starts, then you will have to start buffering, bring it down to 8 or a little lower and you should be ok.


edit: just read that plants are green again, if this is the case and fish are happy, just be patient, the higher PH is a blessing in disguise, buffering PH is as much a pain as bringing it down.