Backyard Aquaponics
A place to discuss aquaponics

Hi I have a 5000 litre tank , in a greenhouse, with a heatpump keeping water temperature at a constant 24 degrees for barramundi.
This is a perfect climate for algae, has anyone used a UV sterilisier to reduce algae? It seems it will kill the algae no problem , but will it also kill off the good bacteria? Seems to me the good bacteria will survive in the biofilter, but would appreciate any good advice ,
regards
MickM

Think it will kill of bacteria in the water but not on the gb media. So it will slow down the cycling. If you shade the ft then the algae will go once the system is cycled.

Thanks for your input- the system is cycled, has been for months - ammonia, nitrites neglibile, but algae persistent, probably because it is in hi-tech greenhouse and constant 24 degree water temp. I was told heat pump wouldn't work and it does, so I guess i will just have to try UV and see.

You can filter out algae as well. I have a 55000ltr tank that goes green after a lot of rain and I just run a filter for a couple of days to get it clean.

What sort of filter? Do you mean run the biofilter 24/7 ? I tried that with some improvement , but not enough. Why does the rain increase algae?
Appreciate your input.
mickM

I've used barley straw in my water gardens in the past. I keep some in my AP system too....the water is crystal clear, just some algae on the side of the tank.

Here's an article on how it's used in larger ponds....

http://www.aquabotanic.com/barleyarticle.html

Re Barley straw- that sounds interesting , and organic too. I'll give it a go, cant do any harm.
Thanks
MickM

Organic

The uv can control but not eliminate algae. Depending on the power of the light it is usually best to only run part of the flow back to the FT through the uv which gives a longer contact time.
It would have no effect on the biofilter if used feeding into the FT and would kill some of the unwanted bacteria.
I assume you have some shade over the FT?
I think what Duff meant by a filter was either a foam and fibre (pillow stuffing) filter to get rid of the initial high load (this would make the uv work better) or an ETS skimmer.
Good link for DIY filters http://www.koiphen.com/forums/showthread.php?t=38259
Esp the ETS by L5vegan (bottom right hand side)

Sorry one more thing put in more plants to lower the nutrient load esp phosphate and nitrogen. The above is really only a short term/intermittent thing unless you don't mind the maintenance power usage .

Another thought might be to cover the fish tank so there is very little light going in.
One way to to this would be to float a polystyrene raft allowing shelter for the barramundi.
The second benefit is that you could cut holes in it and float some other plants eg lettuce or lebanese watercress. The plants would then also extract more nutrients from the water. We have floats in the fish tank on display at garden week if you look at that thread Mick.