Backyard Aquaponics
A place to discuss aquaponics

Good morning
I'm going to drain our two year old 2600 gallon (10,000 liter) aquaponics system. We've had Brook trout in this system for two years. We started with 45 fingerlings in our pristine tank. We caught most with a fishing rod. About ten remained as my wife and I are dealing with assorted health issues.

Recently the remaining trout are getting sick and dying. I netted one yesterday that looked like it had fungus growing on it. It may be the last trout in the system, perhaps there is another. There are five Comets also two years old which we'll place in a stock tank while I sort out a problem with a non functioning SLO.

My SLO is an air lift system. The pipe through the masonry wall of the tank is too small at 1.5" (3.81 cm) so there is a bottle neck at that point. The filters are gravity fed all the way to the 200 gallon (757 liters) sump. Levels of the RFF MBBF and sump are not changeable. The FT is 5.5 feet (1.6764 meters) deep with a natural wedge shape bottom.

I can add a bigger pump to the system but the flow through the filters is what it is the way it's plumbed. I'll do a video of what it looks like ASAP.

I know it is going to be difficult to help diagnose something based solely on the DIY builder's defensive position.
I've got to get an open mind about this as clearly what I thought would and was working isn't.
This issue as I see it is, I need an increase in flow through the RFF and MBF via the SLO. At the moment I can not balance the flow going through the filters in relation to the level of water in the pond and this makes the overflow via a surface skimmer greater. Also compounding the flow issue is the media beds are once again choked with tomato roots.

This Winter after rebuilding the SLO with two pipes in the bottom and two air lifts it was possible to dial in the flow through the filters to stop the overflow completely. Obviously this balance over time is tenuous at best.

Part of the problem I believe is the SLO gets plugged with detritus and algae which slows down the flow though it and changes the balance I set. After a couple times when I saw the overflow increase I was able to pull the SLO and clean it and viola balance was restored.

This time cleaning the SLO hasn't stopped the overflow to the sump only reduced it. The next issue which occurs is the seven inch sock filter plugs within a day and dumps uneaten fish food in the sump. that rotting fish food is covered in fungus.

The way I see this vicious cycle is increasing the main pump flow won't solve this problem only exasperate it.

I can't recall right now which pump I have I think it is the Laguna 600 with Maximum Flow Rate: 2400 U.S. GPH
Maximum Pond Volume: 4800 U.S. gal.
I don't have enough combined media beds and MBBF volumes to handle this flow let alone an increase to next size up: Laguna pump at Maximum Flow Rate: 2900 U.S. GPH Maximum Pond Volume: 5800 U.S. gal.
It seems like I need to go back to the beginning and design this flow system.
Do I need to double the sizes of the RFF and MBBR?
Next year I'll be double the greenhouse size and adding much larger media beds. Should I do another quick fix until then?
Any help would be appreciated very much.
Brian Rodgers

It's very hard to tell what's going on Brian . It sounds from your description like the bottleneck isn't the filters, it's the coarse solids and algae. I don't know if these suggestions will work but I think they would help.

1. UV filter will kill the algae and reduce the blockage (although initially it will cause more blockage until the algae is gone).
2. Coarse prefilter or separate pump and coarse filter - doesn't have to run all the time just to take some of the load off the main filtration so this could be a temporary setup that's only in when it's in use. Like a pump hooked to a pool leaf canister or a 5 gallon bucket SUF.

You didn't mention where in the lineup the filter sock is but it sounds like you also need a coarse filter before the filter sock. The coarse prefilter system would probably help with this.

Water level skimmer>>>> sock filter >>>> Sump.
I am beginning to grasp how large the pool of fatal candidates could be.

My wife thinks it is Dropsy. She wants the UV sterilizer!

I'll do water tests tonight for pH, high range pH, ammonia, nitrite nitrate, GH & KH. At least we'll have a few definitive data.
Last chemistry test was June 3rd 2017 Chemistry 7.2 7.8 0ppm 0ppm 5ppm no KH or GH listed, water temperature 64F
Seven fish died within a two week period.
I just netted the one I thought was left this morning. No more trout in the FT.
Next I'll net the Comets and see if they have ulcers.
No pesticides sprayed outside. No copper in water.
I'm certainly leaning toward a pathogen here.
You're right Scotty435 it could be anything.
Broad spectrum fish disease treatment?

If you don't already have one, a pool type leaf canister on the inflow for the skimmer might help.

It sounds like the water has a lot of particulates and the algae may be a lot of that - If you can clear the water of particulates and treat with UV light I think that might be the best first step, just to kill the algae and with a bit of luck slow or stop the spread of whatever disease this is. It won't do anything for the already affected fish but you can probably treat them outside the system with a dip or temporary home as you're reducing the chance of reinfection in the system. Be careful what you use if the fish are to be eaten or if you think there is a chance something could contaminate the system that you don't want in there.

All Brook trout accounted for, albeit dead.

This is the 2600 gallon trout tank. I can see all the way to the bottom at 5.5 feet.The only place it seems to be dirty is the lowest point in the tank. I can break it up with a broom and the SLO will pick it up. While there is a 1/2" or less thick carpet of algae or moss on the walls the Comets seem to keep it trimmed back.

In one of the photos above the last trout is lying dead on the bottom. I can't tell which because the glare from above.
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Just to be clear it is the outdoor 350 gallon Koi pond which has the algae. A friend from Las Cruses sent me a couple pounds of water garden plants for the Koi pond. Between the raft full of Brussels sprouts and the UV clarifier I'm installing out there I think that algae is going to die off.
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I just emptied this sump and vacuumed it out three or four days ago. Unfortunately, I did not react quickly enough to the trout die-off and only reduced the feed rate to a few pellets at a time not realizing they weren't eating at all.

Here is the layout for the filters. Behind the gray 15 gallon RFF is the maroon 50 gallon MBBF.
The water line in the RFF is roughly the same as the FT water level.

What's that grey RFF filter drum made of? It looks it once held explosives of some sort.

yikes... that barrel scared me just seeing it rusting before I even noticed the explosives!

You are correct, it was a TNT can, probably 75 years ago. It is baked enamel inside, I had thought it was impervious to chemical penetration. I suppose I do need to look at everything in this system. Perhaps I can redesign this part of the system using the maroon 50 gal (189 liter) barrel as RFF and build something bigger and better for the MBBR. I'd like to increase the fish load capability of my system to handle more fish to get me through until I add on to the greenhouse and add more media beds.
What if I added a small pump between the RFF and MBBR?
I've not had enough coffee yet, nevertheless this has opened up some doors in my thinking.
A pump could enable use of a third MBBR or fines filter sitting up on the dirt bed which is 2.5 feet (76 cm) higher. Then add the UV sterilizer off this third barrel which will flow down to the sump.
If a second smaller pump idea can be made to work I can rearrange these four devices for the best efficiency. I look forward to hearing from you..
My goal is: Get water moving faster for the trout.
1>Increase the flow of the system, both the filtration as well as the pump in sump.
2>Clean the wedge shape bottom of the FT as best as can be.
3>Add an inflow to the fish pond to create flow around the pond.

I believe the bottom being shaped with a sloped from one side 9 ft to the adjacent wall. The slope is too steep to stand on when wet, maybe 30 degrees. The SLO is in the bottom of this wedge.