freshwater sump good or bad ?

[Cermet]

Why not build a full sized algae scrubber? It will work far better than any bio-action slump. Unlike a sump, algae consume nitrates, phosphates and other organic based wastes returning almost pure water.

I have an in tank unit but that is because I do not want to deal with a slump system. Can't imagine a better bio-filtering system (of course, it really is the bases for any closed systems, too.)

[scotchbonneteater]

I could put an algae scrubber in the end compartment but would that not starve my bio rings of ammonia/nitrite and therefore I would be totally reliant on the algae ? What happens when I scrape off the algae ? does that mean I lose my BB and get an ammonia spike ?

[Cliff]

Assuming a FW algae srubber and marin algae works the same way, the bacteria will outcompete the algae for the ammonia and nitrites leaving the algae the nitrates and phosphates.

As the algae grows, it consumes the nitrates and phosphates which are removed when you scrap the scrubber clean starting the cycle all over again.

At least, this is all based on what I have read about FW scrubbers. I have only used a scrubber on a marine set-up as I find it a lot easier and more cost effective just to complete water changes on my fresh water tank

[scotchbonneteater]

Thanks Cliff that cleared it up

If I have an algae scrubber wouldn't I still need to do water changes to provide minerals for the fish ?

[Cliff]

Thanks Cliff that cleared it up

If I have an algae scrubber wouldn't I still need to do water changes to provide minerals for the fish ?

Yes, IMO you will still need to complete weekly water changes for those reasons as well as helping to manage the other things in the water we never test for, like hormons

[scotchbonneteater]

So the only real gain is low nitrates and phosphates ? My nitrates don't climb above 5ppm for 3 weeks after a WC but I do keep getting diatoms, I think I'll have a little play with some gauze and see what happens

[Cliff]

Diatoms need silicates to grow, which is likely in your water supply if you continue to get it (I get that from time to time as well).

Try using some chemi pure elite in your filter. It might remove enough of the silicates to reduce your diatoms.

[scotchbonneteater]

Silicates? does that come from silicone sealant? I used fish safe silicone to put the dividers into the sump and let it cure for a week. Hopefully after a few more water changes it will be back to normal otherwise I will have to go down the chemical route.

[Cliff]

NO, silicates is a mineral compound containing iron that can be found in water supplies. It is safe and has nothing to do with your silicone.

Give it a quick google and you will see what I mean

[Cermet]

Algae scrubbers can reduce the number or amount of water changes but not do away with them. Phosphates are always high in aquariums so an algae scrubber removes those and only large water changes done often can offer a similar performance.

Relative to nitrates these are low in your tank, so not a big deal; but mine remain below 1 ppm and my tank has a lot of fish that leave a lot of waste - rather surprised my tiny units works so well.

Algae scrubbers will remove/process other organics that bacteria only partly break down - like hormones or fish slime (yet, so do large water changes) - so, I do feel they offer other avantages. Still, the best action is near 100% water changes done daily but that, for most of us, is way too much effort. Weekly large water changes can be dangerous if the tank pH is changed by doing only weekly changes (depends on your water being soft or hard.)

The issue is does such a unit buy you anything? The scrubber needs the algae removed once a week and if your water changes can handle it, maybe not worth the trouble. Still, since you will have the slump system, might be worth the effort.