Removing Bioballs

[IanF]

I've read on here that bioballs can be a source of nitrates and actually do more harm than good.

My tank has had bioballs in it since day 1 (now about 2 years old), and I've never had a problem with high nitrates (generally around 1ppm, never above 5). However I get a lot of green algae growth that I can't get rid of - I've been through evey on-line guide to reducing algae growth with no success, and I'm wondering if the bioballs & nitrates are to blame.

As I said, I'm not detecting any nitrates in the water - but if the algae is feeding on it then it will be captured as soon as it's produced and therefore won't show up on a water test.

Is my logic correct?, and if so will I get a reduction in algae growth if I take the bioballs out? There are bioballs in 2 places in my system - packed into the overflow weir so the water trickles over them (these are pretty crudded up after 2 years) - and submersed in the sump (these are still visually clean after 2 years) - see pictures below:

Should I just whip the blighters out, or are there hidden dangers to beware?

Thanks in advance

Ian

Other info:

Tank size - approx 300L
Live rock - approx 70kg

NO2 - 0
NO3 - 1
KH - 12
pH - 8.3
Ca - 400
PO4 - 0.03
Density - 1.024
Carbon & rowaphos in sump
deltec skimmer
RO water used, 5% weekly waterchanges

2 clowns, 1 yellow tang, 3 green chromis, 1 sulphur goby, 1 algae blenny

 

[rictheredneck]

dont know much about them but damn all that crap on them cant be doin your tank any good


edit: you tried a fuge in your sump with a cheap ass light and got summat like a sea hare munch all your hair algae away?

 

[kkyyllee]

holy crap theres alot of crap on them!, theres ur problem


if you remove them you have to do its slowly, a handful a week

 

[SkiFletch]

I wouldn't be so hasty... Let's break down what's happening here. Likely the reason your tank has no nitrates is because the nasty green algae is eliminating the nutrient faster than you can test for it. The algae is actually growing and doing the nutrient export for you.

The nutrients are likely coming from detritus and waste trapped in the bioballs and therefore allowed to fully decompose. Removing the bioballs will help remove some of the waste problem, but not eliminate it. You'll still have to cut down on feedings, and vaccum your sandbed routinely to keep nutrient export going.

My suggestion for killing the algae in your case would be to leave the lights off for 3-4 days straight. Your corals will be fine and the algae will likely suffer and die. Once the algae is eradicated, watch out for rising nitrates and phosphates. You may have to consider large water changes, a refugium, a remote deep sand bed, or a combination of those to keep nutrients down.

 

[IanF]

What's the difference between the balls in the weir and the balls in the sump? The set in the weir are not submerged, and it's these that have all the crud on them.

The set in the sump are underwater all the time, and are still clean. Is this just because the crud has already stuck the the earlier balls and/or taken out by the filter mat? Or is the chemistry different?

Thanks for the useful advice so far

Ian