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Need help: Dying plants, unknown floating residue
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Author:  oenoveso [ Nov 8th, '19, 14:20 ]
Post subject:  Need help: Dying plants, unknown floating residue
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Hi Everyone, I need some help troubleshooting my aquaponic system. It used to be thriving but now, the lettuce is showing stunted growth if at all and the other plants are dying. There's some stiff floating substance that's showing in the water that are flakey and I think might be calcium, but I don't know for sure what it is. This is what I'm showing in the pictures. I'm sure it's related to my problem.

My system used to be thriving but it has slowly degraded over a period of maybe 2 months. Changes I had done were that I moved the water pump to a different point in my system and it slowed the water flow a bit. I have since corrected it but the system still doesn't seem to be recovering. The fish are healthy though.

Recent problems are some leaks that I've tried to fix but I still add about 5 liters of water to the system every day which I attribute to plant consumption, evaporation and I guess to some of the leaks. Mentioning this as I suspect it may be part of my problem.

Hope I can get some help and pointers. Thanks ahead.
Author:  scotty435 [ Nov 9th, '19, 00:38 ]
Post subject:  Re: Need help: Dying plants, unknown floating residue
How much is 5 liters in relation to the system volume?

That's a very interesting phenomenon if it is a calcium precipitate because you'd expect it to sink. I did a search though and found some information on calcite rafts that can form when there is very little water movement, it seems to fit your situation so maybe this is what's going on? https://en.wikipedia.org/wiki/Calcite_rafts. Kind of looks like your image. The calcite rafts could be physically smothering the plant roots like fine solids do or it could also have something to do with calcium availability. I can't recall having ever seen anything like this in any AP system :dontknow:

Check the pH and alkalinity of your water and post them up. Water temp and any other parameters you have might be helpful as well. Are you using any form of calcium to adjust your pH and do you alternate with a potassium product? If you have access to a microscope that might tell you if this is some oddball microbial film instead of a calcium issue.

Filtration might be an issue. I mentioned that fine particles can smother the roots and whatever this is could just be something like that so that's another thing to look at.

Hope this helps :?
Author:  oenoveso [ Nov 11th, '19, 15:17 ]
Post subject:  Re: Need help: Dying plants, unknown floating residue
scotty435 wrote:
How much is 5 liters in relation to the system volume?



This would come out to less than 5% total volume of water in my system though. But I didn't know what was normal. Does this sound like within normal ranges? Thanks,
Author:  oenoveso [ Nov 11th, '19, 15:24 ]
Post subject:  Re: Need help: Dying plants, unknown floating residue
scotty435 wrote:
How much is 5 liters in relation to the system volume?

That's a very interesting phenomenon if it is a calcium precipitate because you'd expect it to sink. I did a search though and found some information on calcite rafts that can form when there is very little water movement, it seems to fit your situation so maybe this is what's going on? https://en.wikipedia.org/wiki/Calcite_rafts. Kind of looks like your image. The calcite rafts could be physically smothering the plant roots like fine solids do or it could also have something to do with calcium availability. I can't recall having ever seen anything like this in any AP system :dontknow:

Check the pH and alkalinity of your water and post them up. Water temp and any other parameters you have might be helpful as well. Are you using any form of calcium to adjust your pH and do you alternate with a potassium product? If you have access to a microscope that might tell you if this is some oddball microbial film instead of a calcium issue.

Filtration might be an issue. I mentioned that fine particles can smother the roots and whatever this is could just be something like that so that's another thing to look at.

Hope this helps :?


Scotty, thanks. This is very helpful. I'm embarrassed to say I have not at all taken any pH and alkalinity measurements. It started out really well so I never bothered. I'll get me some kits and see to it. Thanks. The temperature is around 30 to 35 degrees Celsius but that's the air temperature that I measure. Should I be measuring the water temperature?

I think you're right, it's really just too little water movement and I think our water here is naturally hard. I'm using a series of gravel-filled tubs to filter the water but I'm thinking that it's just too slow water flow. I'll change up my water pump soon and I'll see how that changes things.

Thanks so much.
Author:  scotty435 [ Nov 12th, '19, 02:12 ]
Post subject:  Re: Need help: Dying plants, unknown floating residue
While it might not help to know the water temp in this case, it's still a good idea to check this because water temp along with pH determines how much of the total ammonia is present as the toxic form and indicates if you should stop feeding and let the ammonia levels come down. The chart on Total Ammonia Nitrogen located here gives you that information - http://ibcofaquaponics.com/information/tables-and-charts/

One indication that you need to check this is if the fish are off their feed. Another is if the fish are gasping for air at the surface of the water - warm water holds less oxygen than cold water so having a high water temp is a danger especially for fish such as trout which start to die at around 23 C. Considering where you are you're probably not growing trout - my guess is you have Tilapia or some other warm water fish where it might not be much of an issue.

Doesn't seem like your water loss is unreasonable for air temps that high.

Just to give you an idea of how much water flow is typical - Usually with DWC it's good to turn over the volume of water in the DWC once per hour but I've seen once every one to four hours listed before. Typically we aim to turn over the water in the fish tank once per hour as well. You can be flexible on this as these are only guidelines.

Cheers
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