Backyard Aquaponics
A place to discuss aquaponics

So, fell in love with the concept of aquaponics a couple years ago, but didn't have the space to put it. Moved into a new house, had more open space, but the wife was too leery about the idea so I decided on a small system with an herb garden. It's a little 10 gallon aquarium with an 18 gallon tote as my media bed.

My media is just some pond pea gravel. I tested it in some vinegar over a couple days and nothing foamed, so I figured the fear of any limestone was taken care of.

I put the system together, started it up and let it run for a good week empty, then added in four basil plants that were already partially grown, five tomato plants that were just past seedling stage (about 1.5" high), and three pepper plants of the same size.

I let that run for a good two weeks before I added the fish (May 7). I bought a dozen feeder goldfish from the local pet store. For 40 cents a fish and a small tank, I figured that's the way to go. Had the expected nitrite spike and in a week, lost 7 of the 12 (by May 15). Another two weeks later, and I bought another dozen fish (May 30) bringing counts back up to 19.

These guys did a good bit better, however I think I'm down to about 7-8 fish again, having lost almost one a day for the last four days. The ones surviving ARE some of the bigger ones, possibly even from the first batch of fish. Still, losing that many fish is really troubling.

At this point, everything is fully cycled

• Nitrates are around 5-10 ppm
• Ammonia tests are barely 0.25ppm
• Nitrites aren't even at 0.25ppm
• ...but pH is consistently around 8.0.

The store I bought the fish from said rather than pH down, I should use a buffer, and as everything I read said we should be in a 6.8-7.2 range, I got 7.0 buffer powder.

The fish are fairly well-oxygenated as far as I can tell (no one is gasping for air at the surface). The best timer I could find had 20 settings, so I have a 20 mins hon, 54 mins off cycle to cover the day. I have a bit of an algae problem, but it's mostly just greenish slime/biofilm on the hoses in the water and on the tank wall. (Planning on putting a screen around the tank to get rid of the sunlight.)

• It seems like every time I add the buffer, I start losing fish.
• It seems like every time I add fresh water (to top off the tank, I lose fish (yes, I'm off-gassing for a couple days).
• It seems like every time I do nothing but let the system run, I lose fish.

Things SEEMED to be working well and improving, but the last several days of losing a fish a day is starting to get to me. Should I keep trying to push the pH down with the buffering agent, or is there something else I'm missing?

If you're loosing fish whenever you use the buffer powder, then stop using it. You might be using too much, and it's causing a PH swing that's taking out a few fish.

The system can work well with a high PH, it won't crash and burn. If it hasn't come down after a few months naturally, then you can look at something like hydrochloric acid in your top off water to eat up some carbonates. But leave it alone, and see if it comes down naturally.

When the fish die, is there anything visably wrong with them? Blotches on the skin, very red or bleeding gills, holes where a bird has eaten half of it? Or anything else that it might be?

Also, your system isn't that large, is it out in the sun? Temp swings would be very fast, the fish might not be coping if you're going through a hot period.

what are your temps like?
small systems can swing quite a bit
is it outside?

I've got it on wire cart sitting next to our north-facing sliding door. Temp swings SHOULDN'T be too high, but that was one of my thoughts.

Last night, I went ahead and did some maintenance and just completely scrubbed the lines, pump, and scrapped all the algae off the sides. I know some biofilm is helpful, but I decided to give it a fresh start.

In addition, until I can take the time to make a curtain to go around the sunward facing sides of the cart, I cut a cardboard box so it fits around the sides and part of the top of the tank. I'm hoping this'll keep the algae down but if the temp swings of sunlight on the tank are also of issue, this should keep the tank at a more constant temp.

Six fish and counting...

I'l recommend finding yourself a temp probe. Get a little one from a catering store, they are quite cheap.

How often are you needing to top up the water?

Maybe every week or two.

I'm a chef by trade and I work for a restaurant supply company. I've gotten so many sample thermometers it's not even funny. I'll dedicate one to the tank...and make sure it never goes inside of any fish I plan on eating.

As an update: still six fish. Too early to tell if algae growth has been inhibited. I'm also feeding them a bit less (mostly as there are only six rather than 10+). They seem MUCH more active since the tank has been covered; dancing up to the exposed side of the tank. It's like they're prisoner's banging on their cell bars!

My son and I are going camping next week, so I'm just going to let the wife feed them and see how the system does. No sense adding in any further variables right now.

Question: For this size of a tank, with the plants that I have stated, would adding more fish be the wrong thing to do? The six left aren't even two inches long yet, but it just seems like it *should* support more fish.

Are you sure your water treatment plant uses chlorine still? A lot of USA water plants are switching to chloramines. Chloramines are cheaper and have less nasty breakdown products BUT it doesn't offgas.

In USA, water treatment is required to tell you what system they are using if you ask. Chloramines can be broken down buy vitamin C. There are threads on here with amount per gallon.

Margali, I'll check into that. Hadn't even considered it.

As an update, last week my son and I went to summer camp, and all of the fish survived...until Sunday morning when one showed up dead. Grrr.

The cover over the tank eliminated every bit of algae build up within the tank. The hoses look disgusting, but they get full light. I'll work on covering them next.

In even better news, the pH is finally dropping. I finally got a decent reading on the normal pH test rather than using the high pH test. Ammonia and Nitrites are still way low, but Nitrates have been low as well. Is that because there aren't enough fish feeding the engine?

I'm considering getting more fish and/or a heater. Which do you all think would be the better option to do first, or should I do both?

Goldfish can survive in temperatures down to 34 degrees F and upwards of 102 degrees F. My FT fluctuated by as much as 15 - 20 degrees F in a day with no adverse affects. Don't think you need a heater.

So, I'm fairly convinced now that it's less of a pH issue and it's instead a temperature issue. For several weeks now, haven't lost a single fish since I've been using the buffer and had the curtain to shade the tank from the window behind it.

However, this last weekend we had some nice weather and opened the windows/doors to let the breeze through. It was cool the one day, then the second day it got REALLY hot and muggy which lead up to a storm. Closed the windows, turned on the A/C and over the next four days, I lost three fish.

I'm still losing only "the runts of the litter", sit may just be that, but the temp flux is really what's doing it I think. Eventually I'll shell out for a heater, but until then, I'll just try to be more careful about how much fresh air I let into the house!

Thanks all for your assistance.

I started my system with goldfish too, and kept loosing them. I think it was temperature as well. Too hot for them outside this time of year. The change in temps stressed then and then they attacked each other. I switched to minnows and they seem very happy. Just bought ten more today since my nitrates are still at 0

I started my system with 5 feeder goldfish and five yabbies. Three yabbies died overnight… and one GF got stuck in the pump! This was back in June. Now I have two growing yabbies and one GF.
I noticed that the GF were sleeping overnight on the floor of the FT and the yabbies were more active and 'annoying' the fish. In hindsight, they were more than annoying them!
Plan is to either separate yabbies below a screen or out of the FT all together.
BTW, I only have a blue barrel system.