Backyard Aquaponics
A place to discuss aquaponics

Fish have not been eating well for the last couple of days. Tonight they didn't eat any of their food.

pH: 6.4
Ammonia: <.25
Nitrite: 0.5 !

Advice?

I added some pond salt I have around. I netted out the uneaten food, and changed out about 15 gallons (of 250).

If it is pH that is causing the nitrobacter to crap out, would baking soda help to fix this? Note that I don't have any plants in this system so no worries about the sodium. Tomorrow is Thanksgiving and few stores will be open.

You're my only hope!

BTW, have had oyster shells in the drain flow for over a week and the pH hasn't budged. My pH has been 6.4 since February. There is more solids built up in the gravel, and I'm wondering about the DO in the beds now, since I didn't have this problem throughout the Summer despite the low pH. It has also been cooler downstairs this week and at first I thought the temperature was the reason why the tilapia weren't eating well - the water temp is in the low 70s/20s.

I read in the useful info that nitrate can get converted to nitrite in low oxygen conditions. Should I remove my RSG planter full of sand? Could it be generating nitrite?

Dave

Link http://www.cichlidcity.com.au/-forum-/k ... ticle&k=75

Don the FF put it up on the forum. Note the comments on ammonia and nitrite and the different ways of dealing with them.

Hi Sleepe:

Thanks for that and Don thanks again for your info! I will steal the pump from outside and try to increase the DO.

Baking Soda (Sodium BiCarbonate) will work just fine DD.... or if you can get it Potassium BiCarbonate, as Janet uses, will do the same job and contribute Potassium to your system as well.

Yep, I will look into the pH after the spike is passed.

Took the 200 GPH pump from the system outside, hooked up what I call a "percolator" setup - an elbow to a long pipe down into the water. The water churns a lot at the elbow and the bottom of the pipe produces bubbles like a bubbler does. Removed the solids basket and RSG sand planter, which increased the bubbles from the drain greatly. Increased this even more by putting an extension on the drain pipe and angling it in, it produces huge amounts of aeration this way (sometimes the water makes a sheet all around the pipe circumference like a rocket) and I think I will keep it even if all the fish die haha.

The low pH is probably the root cause of the ammonia/nitrite spike. I'm guessing that you can't measure below 6.4 pH, so it could even be lower than that. The bacteria is definitely not happy that low. Slowly bring your pH back up to around neutral and the bacteria will re-establish in a couple weeks. In the meantime, feed very lightly and monitor water quality.

Baking Soda would be fine, and potassium bicarb even better. Monitor pH daily until things straighten out, and then weekly.

Thanks JP!

BTW, today my stepson's biology teacher came over to our house to see the system(s). Apparently he majored in aquaculture and has a lot of experience with tilapia (helped grow hundreds of pounds of them in college). He has a pond and I could get bluegill from him if I wanted. He might be putting an aquarium in the classroom soon and take some tilapia from me.

He mentioned RBC (rotating biological contactor) biofilters as having better oxygen levels than gravel flood and drain:
http://en.wikipedia.org/wiki/Rotating_b ... _contactor

Nitrite between 0 and 0.25 this morning and just checked it again (after my 2 hour Thanksgiving nap) and it's still a trace not quite clear yet.

Have been checking nitrite before feeding, sometimes it has been a trace and sometimes it is up to 0.25. I don't feed when it is higher than a trace, and I have not been feeding them as much food. I got half a dozen boxes of baking soda and will be adding that and monitoring pH as we go forward together on this AP journey...

I think if I get enough free time I may eat one of them. The three biggest ones are definitely getting to be impressive.

Been eatin' for a while now. You're slow.

I'm waiting for them to get as big as the ones at Epcot. I figure it will be easier for a fish-killer-newbie like me to cut them up if they are bigger!

Bounced my pH up to about 7.2 with the baking soda I added today, guess it was too much. Trace of nitrite (<0.25) but the fish are very hungry.

Glad things seem to be on the mend DD.
I had the same issue with my silvers in the spa setup. Once i moved that system i was running the spa pump for an hour or so each day. It just wasn't enough. I had reasonably high nitrates which started to reconvert to nitrite in the anaerobic environment and killed several fish. Took me a while to work it out.

You may notice some browning in the gills of your fish. There may be some blood like stains on their skin surface. These are indicators for fish stuck in a high nitrite environment. It sounds like ur husbandry skills has saved u from fish deaths. Well done!

Further to the probable causes of ur fish deaths, those anaerobic zones at the bottom of ur gbs do sound like the issue. I don't recall ur gb setup. Are u able to take them offline one at a time and give ur grow media and bed a good rinse in clean water?
If u did one bed a month over the next 3-4 months your bio should be ok. Don't do them all on the same wknd, it could knock ur bio around and then you would have the same problem for an entirely different reason.
(You prolly know all this stuff, but it helps me reinforce it in my own mind.)