Backyard Aquaponics
A place to discuss aquaponics

I have an IBC tote aquaponics system that has been running for about 2.5 years. I have a heated tank in which I grow tilapia. My tank holds about 250 gallons (950 L) of water and my sump holds a max of 180 gallons (680 L). About 2 weeks ago, we had a hot spell. I am in Los Angeles, California and it was in the 90s (30's celsius). My sump ran low and the pump stopped pumping water. I lost maybe 5 or 6 fish. The water tested fine so I added maybe 160 gallons of tap water, which I have done every few weeks for the past 2 years. The next couple of days I lost a couple more fish so I assumed that the fish died from lack of oxygen as the water temperature had increased maybe 10 degrees Fahrenheit. So, I cleaned the air stones to increase dissolved oxygen. A couple days later I lost a couple more fish, so I went to the store, bought salt, new aquarium stones, new water testing kit, and an organic anti-microbial named Artemiss. I stopped feeding the fish and I used the Artemiss for 5 days, finishing the bottle. I ran out of the Artemiss maybe 4 days ago. I started feeding the fish 2 days ago. Today there are two dead fish lying on the bottom of the tank. Today the ammonia tests .25 ppm which I attribute to the dead fish. Nitrate is 0 ppm and nitrate is 0 ppm. pH is 7.2. Water temp is 76 Fahrenheit. Does anyone have any idea what is going on? One thing to note is that the bigger white fish are dying. The smaller blue tilapia seem to be doing okay.

I would suspect you are seeing a die off from the stress caused by lack of water flow, low DO and high temperature. How long was the pump not functioning? At those temps, it is very difficult to keep DO up to required specs. How many fish are in the fish tank and what is their size/weight? Sounds like the water temp has fluctuated a decent amount as well.

As a side note - Artemiss is not safe for food fish according to their docs: "This product is intended for use with all ornamental and aquarium fish only, and may not be used for fish intended for human consumption."

I second ebeuerle on this. It seems likely that the initial problem was the cause for these deaths.

As far as the use of Artemiss, it seems like it should not have been used since the cause of the problem was not known and as was noted it isn't approved for this use. It's your call though

So what happened to the original 160 gallons you lost? And how safe is your tap water? Mine kills fish in a few days. Even if it sits for a week bubbling away. You need a low water alarm made from a smoke detector. A 40% water change from tap water is not the best thing to do IMO. How many fish were in the FT? More then 50? I can't see a pump failure killing the first 6 fish as long as the air was on, seeing you said your numbers were all fine. Fish need water, air and then food. Fish can stay alive in a bucket for months with these 3 and a change of water. Do you think any of the 3 changed. Did the air pumps get near a solvent or paint? Did the food change or even the tap water?

Lack of oxygen is lethal for fish. When DO goes too low in a tank fish can't breathe normally and that causes them to stress. If DO is low for a few hours then that causes so much stress in them that their immune system goes down and due to that fish start to die.

Those with weaker immune system will die first and even if you add more Air stones and a lot of flow even then a few more will die without a doubt. That's why you will see dead fish even after adding Air pumps.

Last year due to lack of DO all 17 of my Koi fish died. And they died one by one. They kept dying even after adding Air pumps. After adding new Koi fish I added 7 Air Pumps just to be on safe side with 3 water falls. Never lost a fish due to lack of DO again.

Don't fish that die of Low DO have their gills turn red? Did that happen to the fish? Reading the OP it seems it had nothing to do with DO, unless all the air stones were in the sump. Trout might die if water flow stops. But blue tilapia?

My main tank was initially stocked with about 35 fish, maybe 4 inches long. We had a heat snap when the temperature was in the 90s for maybe 2 weeks and the 160 gallons were lost to evaporation (the sump was maybe half full at the start.) The air stones are in the main tank and were never off but gradually get clogged. The gils were slightly red, I guess, but nothing extreme or like pictures I have seen of fish dying from low DO.

The tap water here is not perfect but I use a tap water conditioner and I have done water replacements like this periodically for the last 2 years. My concern is that fish have been dying in ones and pairs every day or two since the pump failure. I believed that I had addressed any problem at the beginning but kept losing fish every couple of days for 2 weeks. I have had die offs before but not that kept going for so long. It sounds like from abhinav1986's post that this isn't uncommon. Could I just be experiencing fall out from that initial event?

Yes.

I still don't realize how a dry sump would kill the FT fish. These fish had water air and maybe food. As long as the air was flowing they should be able to stay alive for months. They are not a fish like trout that needs a good flow of water. They can live in a bucket if need be. Something else must have entered the water. Something the fish don't like to live in.

I used to use my tap water and also local well water and they both went to fish poison overnight. I can't trust either of them now for drinking, fish or plants. Did anyone toss in something you are not aware of? Even a plant or use some cleaner to wash something. Bleach will kill them, if in a really low concentrate it will take them out slowly. It sounds like a pollution problem.

I might be tempted to take one fish out to a bucket of same temp tap water and see if it dies off over night. Place an air stone in it.

Sounds like the air stones weren't really working at first and there was no water movement so no air being added this way either. I don't think dmburns has mention how many fish were in the tank either but he is growing tilapia and there were probably a lot. It doesn't look like the water temp really got that high so I'm not sure if this played much of a role in the low oxygen levels or not. The temperature fluctuations might have stressed the fish a bit though . No mention of algae which could also have played a role. Another thing, it would be good to know if the fish were gasping at the surface when he initially found them.

I have never had an air stone get so clogged it failed to work. How does one neglect a system so long that 160 gallons of water evaporate is the big question I have. Maybe the fish have an auto feeder and the system was neglected because of life getting in the way. I would think, it had to take a long time for that much water to evaporate.

I do know that when life problems arise, many things get put aside and my guess is that you were lucky not to lose the entire system. 35 fish for 250 gallons still has room for at least 15 more full size ons so there was enough fish room.

If you run into this problem all the time, I suggest that you look up smoke detector low water alarms. They are cheap to make (hack) and loud enough to hear. If the system is too far away to hear then a better alarm is needed, maybe even one that calls you.

You could always add a new water float switch to the sump to add water automatically. Similar to a toilets plumbing. A few bucks and an hour of time. That is the safest action. Put in 2 if you worry about a failure and add an overflow to a drain if they never turn off. They are just for evaporation make up and don't need to be on at full blast.

Thanks Deuem, I missed that fish count when I skimmed back over before posting .

No problem scotty,

On the air stones, I have never even once had them cake over and stop pumping out air. What would cause this? Calcium in the water? Not enough air to the stone to begin with? I know that over a period of time they seem to start losing some strength due to internal loading of crap. This is why I always have a box of new ones sitting under the FT. They cost a buck each here. Maybe after 5 to 10 years they wear out or the air hose to the stone breaks but I have never had one fail. CLOG and stop. It is the second most important thing for fish. It is why I now feed my FT with 2 air pumps. If one gives out, I still have the backup running 24/7. I also have some battery back up pumps if needed.

The sump's capacity is 180 gallons. It was about half full before I went away for a long weekend. At about 40 gallons the pump starts to run out of water, so the loss of water was 50 gallons. At 98 degrees with the amount of plants I have and with the dry Santa Anna winds blowing from the desert, I can easily lose that amount of water in 3 days. The real heat and winds started the day I left or I would have topped off the tank. It went from highs of 70's to highs of high 90's.

By the way, I never said the air stones stopped working completely. I said that I suspected that they were clogged and not properly aerating the water so I cleaned some and replaced some.

I have done water replacement with a tap water conditioner of this size for the last 2.5 years without a problem. My pump is on a timer and doesn't run at night. I typically wait until evening, fill the sump with tap water, add conditioner and air stones and let it bubble all night. All tanks are insulated so the temperature drop in the morning when the pump comes on isn't too extreme. Grow beds are not so there is an unacceptable water temperature drop if I run the pump at night.

I lost another fish today. Water quality is good, all stones cleaned or replaced, temperature is good. No algae, I haven't been feeding the fish. This is either fall out from the initial event a month ago or something else is going on. Maybe it is time for a complete system cleaning and water change. It has been a while since I've done that so I guess I am due.

Always tough to say but it still does sound like fallout from an initial event. Usually it's some physical parameter like oxygen or nitrite.