Backyard Aquaponics
A place to discuss aquaponics

I am trying my hand on a small scale with aquaponics to learn before I expand to a larger system. Right now I have a 29 gallon fish tank. I was given an already established aquarium setup and am trying to get it to cycle. I currently have 3 spinach seedlings and 3 lettuce seedlings in the grow bed. The plants do not appear to be doing well as the lettuce is quiet yellow and the spinach has white spots on the leaves. They also are not growing much at all. A couple of the fish (guppies) have died but not many (3 or 4 in 6 weeks). The system is in my house as I do not have a greenhouse yet. The grow bed has an LED grow-light and the fish tank has a fluorescent light. Both lights are on a timer which runs the lights for about 14 hours a day. Until recently I only had an API pH test kit as getting an API Master Freshwater Kit took some time. During the pH testing all of my readings were at least 7.6. I am not sure exactly how high it was as 7.6 is the limit. I finally got the Master Kit and the initial readings were

pH- 8.5

Ammonia- 0 ppm

Nitrate- 80 ppm

Nitrite- 0 ppm

In my search online I am not finding what I need to do in order to help the system cycle and get the pH down.

Any direction would be greatly appreciated!

There's advice on many previous threads about getting pH down. Essentially you need to use hydrochloric acid and add it to a seperate container of water, leave it for some time so the chemical reactions that adjust pH have happened, and then bit by bit replace your fishtank water with the new pH adjusted water untill your pH is where you want it.

It will happen naturally over time thuogh, without adding anything. Eventually you will need to take measures to raise rather than lower your pH. It sounds like your tap water is very hard? Perhaps you could collect rainwater for a better pH top up water?

Its not surprising that the plants aren't doing well at that pH, these things take time to settle out. Just replace the plants and keep trying, eventually it will work.

You have plenty of nitrate and no ammonia or nitrites, so the system seems to be cycled.

More plants or less fish food will bring the nitrate down... though it's not at dangerous levels.


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Be careful using HCL acid for PH down as it can accumulate Chlorine in the system which can lead to problems with your plants, in a new system its better to use Phosphoric acid as its one of the safest to use and adds a little phosphate to the system which will benefit the plants.