Backyard Aquaponics
A place to discuss aquaponics

Folks, I have a small system that has had fish and worms going for several months, but plants totally struggle and I'm trying to figure out what the issue is.

I'm following the recommendations of Sylvia Bernstein in "Aquaponic Gardening" and have the following system:
* What the book calls a Constant Height One Pump (CHOP) system
* 20 gallon fish tank with ~12 healthy active goldfish
* 40 gallon plant bed filled with Hydroton clay pellets and a Bell Syphon (bead drains and fills every few mins)
* 30 gallon sump tank with a pump that runs all the time leading to the fish tank

I'm targeting a pH of 6.8, but the pH does creep up with water additions and passing time. I have been correcting it periodically with "pH Down". The fish have been doing great for months and I just dug around and the worms are doing well also. So, I imagine I have a healthy bunch of bacteria in the bed. But, plants just do horribly. Can you see the image of a basil plant that I have in there. The tip of the leaves turn brown and there is a general "failure to thrive".

The book leads me to believe that the Nitrogen, Phosphorous, and Potassium are self regulating in a healthy system and all I need to manage is pH, but I have no confidence that one or more of those is totally out of control and I don't currently have a way of testing.

Can someone help me out with a suggestion?

Many Thanks, Carl

There's only really one input into the system to help your plants grow, feed... Try changing your fish feed or feeding more to the fish.

You could also try peeing in it a few times to get things moving quicker but before you do think if you have taken anti biotics recently as that will make things worse. It is a problem if you have trout. You have too many and then you put them all in the freezer before the hot weather kills them, then you don't have enough so you can help the system along a bit. Tomatoes and strawberries love it.

You’re keeping the fish alive, so all is not lost. Do you test other water parameters like ammonia, nitrite, and nitrate? What is the water temp? In order to increase the fish feed, as suggested above, you will probably need a larger fish tank. Twelve adult goldfish will need 100-200 gal. to remain healthy. I would also suggest growing greens for now, as fruiting plants are a bit trickier. And I think many folks find they eventually need to supplement minerals like potassium, calcium, and iron. I am relatively new to aquaponics, but have learned loads from this forum. Hopefully others will have more suggestions.

Also, I see that you’re in a cold climate so am guessing your system is indoors. Basil likes a lot of light and heat.

Thanks for the help. My set-up is inside. My ammonia is 0, Nitrites is 0, and Nitrates is ~ 80 ppm. Temp is 77F / 25C.

And, I have two LED lights that claim:
* Actual Power Draw: 100W±3%
* LED Quantities: 300pcs SMD LEDs
* LED Color: 3500K, 5500K, 660nm
* HID Replacement: 200W HPS/MH

Per suggestion I changed feed, am feeding more and added gold fish.

Questions:
* What is a good range for Nitrates?
* Any practical ways of testing for phosphorous or potassium?
* Since all the plants died, I'll be replanting. What should I try?

Thanks!

I don't think nutrients are the problem.It's those LED lights.Almost everyone who has those lights,has a problem with their plants.Notice the leaves look burnt?,probably because they are.

20 gallons/90L tank is too small for 12 gold fish & they are cold water fish 77F/25C is too hot for them long term.Lower the temp to 68F/20C.

I read you changed the feed,but what were you feeding them before? & what are they having now?.
You also mentioned HID,did the plants grow under them or the LEDs? and how big did the plants get before they went bad & died?


1.Nitrate,as low as possible,try to keep it around 20-40ppm.Too much of one thing might cause a lockout of something else.
2.There are test kits on amazon or ebay.
3.Beans,peas & chard (to name a few) are very easy to grow in these systems.If this is a heat issue,forget the peas.

Folks, Is the 80 ppm of Nitrate high enough that it is hard on the plants, or is that more of a fish issue?

I just have almost the same problem! I would be very glad to receive expert advice! Thank you for your attention and thanks in advance for your answers!

Some of the wisest people on here say high nitrate will harm fingerlings and make plants taste bitter. But others, including me, have run nitrates at much higher levels than 80 and fish and plants have been fine. I doubt they are your problem.

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