Backyard Aquaponics
A place to discuss aquaponics

Hello,

I've had a home-built, indoor system running for about 18 months now. It's done fairly well, but it seems unable to grow certain plants. I've had 5 goldfish in it since inception and none have died (all have quadrupled in size). I only add water occasionally, and feed the fish daily. The grow medium is clay pellets; the water flow is ebb-and-flow on a timer, up to 4x daily. There are no grow-lights; all light is natural sunlight from south-east facing windows (best I can do).

Here's a picture.

https://pbs.twimg.com/media/CZDAWvKUoAEmtyc.jpg:large

It has very successfully grown: basil, mint, oregano, kale, decorative bamboo, and a houseplant. These plants grow extremely well. In fact the basil lasted 8 months even though normally indoor potted basil lives a month or so, and it also quadrupled in size despite many harvests of it. When it finally slowed down, its root system was enormous.

Most other leafy greens rapidly die, however. In the picture is lettuce, which is on its way to death after about only two weeks in the system. I've killed chard, green beans, parsley, bok choy, all within about two weeks. They all go the same way: initially they perk up; then they wilt, go brown, fall over and rot.

I'm wondering if the addition of growlights or heat would make any difference. The Ph seems fine, always about 6.4-7. The other test that concerns me is that the system water always seems very hard, although the tap water around here (filtered through a Brita filter) is normally pretty soft.

I'd love to hear if anybody has any ideas about what I could do to grow lettuce and other leafy green successfully in a system like this.

Welcome to the forum Atlas3650

Hi atlas3650,

Are you testing the water? Folks commonly test for pH, Ammonia, Nitrites, and Nitrates.
If so, please post the numbers. There are a lot on this forum that have worked though the
kinks and come out the other side with happy plants. If you don't have a test kit, you can
probably take a water sample to a local pet store and get some clues about water health.
You might have some combination of chemicals locking out critical nutrients.

Are you feeding the fish with common flake fish food? It might be lacking important
minerals (like iron, or potassium.)

Post some more detailed fotos and someone might be able to peg the problem...

--
Sam

very good for such a small system

Hello, Thank you for replying!

I am feeding them fish flakes. Originally I was feeding them pellets but ran out. It'd be fascinating if that was the root cause. If so, what food would you recommend?

I have a full spectrum water kit, so I will run the test tonight and post the results here.

Hmm, looks like the leaves on the side away from the light are dying first.

Skrettings and Purina pellet type feeds both work - basically commercial fish foods that are designed for growth not maintenance, that's what you are after.

Hello,

I tested the water. Here are the results.

https://www.amazon.com/clouddrive/share ... _link_copy

What worries me is the nitrite level.

what do you guys think?

Thanks for all your help!! :-)

When I look at what I just shared via amazon it looks cut off, so I'm also going to try to attach the jpgs here.

Hi guys,

any feedback for me? :-)

Thanks for all your help so far...

I would say that the nitrite test is unreadable since it didn't react to match any of the colors on the kit. I also think that your pH could be way to low since it reads as the lowest value your kit can read (but with even lighter color). Along those same lines if the alkalinity reading indicates you have very little buffering to help counteract the acidity (no surprise really).

You really need a nitrate test to see if the nitrate levels are high and give an indication of whether you are cycled. A better nitrite test would be nice as well. If the system is well cycled then nitrite will not usually be present for long enough that it is measurable. In other words, you might have a trace of ammonia and then nitrates but no nitrites. This is usually but not always the way it works because the conversion from nitrite to nitrate is fast.

I think you need to bring the pH up or your bio-filtration might crash. Use caution since raising the pH makes the ammonia change to a more toxic form (and this could affect the fish). Check the table here - http://ibcofaquaponics.com/information/tables-and-charts/ to see if the ammonia levels are too high with your current pH and temp and to find out if you're going to push them to toxic levels.

Adjusting the pH
Note - for raising pH - There are several different ways to do this - from most basic to least basic --> Hydroxides, Bicarbonates, Carbonates. Do not change the pH by more than .4 points during a single application (per Rupe).

The effect on pH and the amount of the chemical you use will be different than anyone else because your water is different.

Several options for the adjustment - the first two aren't buffers and the last two are. It's possible to buffer the pH too high (that's why using a mesh bag with the shell grit is recommended - it allows you to remove the bag). Without a buffer the pH will change more rapidly. Some people use a combination of KOH and Ca(OH)2 which they alternate so that they get the nutrients they want. Others just use shell grit or Potassium carbonate or a combination of both. I think both is better since you want to maintain a balance of potassium and calcium. To a certain extent it depends on your water and how easy it is to keep the pH where you want it.

Potassium Hydroxide (KOH) - Used to raise pH and add potassium. 1 T / 1000L every few weeks.

Calcium Hydroxide (Ca(OH)2) (Hydrated lime or Brickie's lime or slaked lime) - Used sparingly and with caution (caustic) to raise pH and add Calcium. Probably adding about 1 tablespoon per 1000L until you figure out what works for your system is a good start. Remember not to change the pH more than .4. Contains other things like magnesium and doesn't add carbonates.

Potassium bicarbonate - A bit less powerful than the two above but works pretty well I'd start at about the same level so 1T/1000L but give it some time to dissolve and let the pH stabilize.

Shell grit - this is placed in a mesh bag and allowed to slowly dissolve, in the process it adds carbonates to the water and buffers the pH up. This is better for maintaining the pH within a range than it is at bringing up the pH after it's gone too low. Nitrification forces the pH down and sometimes it gets going fast enough that the shell grit can't keep up.

Hope this helps

A window doesn't provide enough light. Get grow lamps, or move it into the sun.

+1