Backyard Aquaponics
A place to discuss aquaponics

Hi everybody,

I am very new to the aquaponics field but I am trying to learn as much as I can. I have read lots but still feel ignorant. My wife has agreed to allow me to put together a small system on our indoor fish tank which I have done. My tomato plant went from 3 inches tall to over 4 ft tall in 3 weeks. My question is this, I have checked the water and the ph is between 7 and 7.5, the nitrite is reading 0, the Nitrate is reading very high at 160. The Ph is 7.5, the alkaline is high, and the water is showing very hard. Is the nitrate ok? Should I do anything about the high alkaline? Should I do anything about the water hardness?

Thanks for all the help!
Mark Barnett
Midland, TX

If your nitrates are high then you could probably do with a few more plants. nitrate is less toxic that ammonia or nitrite but some quick growing leafy lettuces would help, tomatoes are heavy feeders as well so maybe another tomatoe plant.

PH seems OK, lots of veges like things on the acidic side but 7 to 7.5 is not to bad. You could knock it down a little and see if the plants grow better.

Are you fish happy with the water hardness? If so then I wouldn't worry to much.

You need to add more plants to bring down the nitrates, how large is your system? How many fish do you have? What is the size of your grow bed and how long have you been running it? Is the tomato under lights, is it tall but with little leaf growth?

Your ph should be ok mine is always at 7.5-7.6. could your nitrates be high from before you added the growbed?

Ok, so this is a plant bed added onto a pre-existing wife's aquarium. Tell us more details about how the system runs.

Tall lanky plants can be a sign that they are stretching for light. Is that the situation with the tomato?

Nitrate of 160 (or higher) is higher than you need though not an immediate panic situation. You might need more plants to use up the nitrates or you may still need to do some water changes to bring the nitrates down into the middle of the chart range. Most of us growing eating fish don't worry about really high nitrates on occasion since we don't intend to keep the fish for years. However, with the wife's aquarium, if any of the fish are really special, you probably want to keep the long term nitrates down in the readable range of the chart.

As for hardness and alkalinity, what ever the fish like is fine. If the fish wouldn't mind, some sea salt say 1-2 ppt could help provide trace minerals for the tomato. I won't suggest maxicrop or seasol since your wife probably would not be happy with tea colored water in the aquarium. Alternatively, there are aquarium fertilizers meant to help supplement planted aquariums. They tend to cost a lot but would also help out the tomato plant (be sure to follow label directions closely.)

Hi everyone, thanks for the input. My system is actually a very small system. The fish tank is a 10 gallon aquarium with some mollys in it. Not any expensive or rare fish. My wife was very leary of me spending money on aquaponics since she had never heard of it, so I bought a plastic tub, the kind that will slide under your bed, placed some gravel in it and placed it on a rack above the fish tank. I have a very small submersible pump that runs continiously running into the corner of the tub. On the opposite side of the tub I have cut a hole and placed a drain back into the aquarium. It runs continously maintaining the water level. The water level is about 3/4 inch the rocks. I wish I had a deeper tub but that is not in the works right now. I am attaching a few small pictures.

I do have a contact for some 50 gallon plastic barrels so I am going to start building a bigger system this winter. I am hoping I can find out how to buy some Talapia.

Verry nice set up! I have one just like this which I set up as a "proof of concept. I would just add more fast growing leafies to keep the nitrates in check. Cilantro, Basil, Spinach, Lettuce - take your pick. Or which ever the owner of the Aquarium prefers!