sponge in sump(purpose?)

[dmbnpj]

Is the only function of the sponge in the sump (i have a big black sponge between the drainage part of the sump and the return part of the sump), to not allow snails and such to crawl over to that side (assuming you might have them down there)?

[gillies]

It is to strain out particulate matter/detritis. Many folks on this forum may advise to remove it - I'll let them explain why. I, on the other hand, would keep it. I don't use a sponge, but I do use filter floss (same concept) in my sump for this type of mechanical filtration. I get as much, if not more, garbage out of the tank using this method than my Deltec skimmer pulls - and I love my Deltec!. If you choose to keep the sponge, I'd would suggest removing it once or twice a week and rinsing it out thoroughly - you don't want the waste it collects to break down, as this starts a nitrate issue.

[dmbnpj]

gotcha, i do have high nitrates....heard that was the bio-balls so those are gone now....guess i will start cleaning the sponge too

[gillies]

Bio Balls get a bum rap. What they really do is expand the capacity of your tank to handle unexpected bio loads like a fish dying or similar occurance. I personally think that good skimming, proper feeding and regular water changes mitigate any chance of nitrate buildup if they are used. Again, most on this forum will disagree because they get their info from Germany. Oh the shame!

[Blown 346]

If bio balls arent nitrate factories why do the nitrates go down or disappear after they are gone? With good skimming, proper feeding and regular water changes how does that effect the boi balls? I can see feeding affecting them by holding the uneaten food and waste. How will water changes and good skimming help if the skimmer is placed after the bio balls?
I have bio balls in my FO and the only way to clean them is to take them out and shake them vigorously. I dont understand how they wont build up junk, I dont think that is a possibility.

[gillies]

Good skimming and light feeding eliminates the organic material Bio Balls would process into nitrate. If it isn't there, it won't get processed. If you have buildup of organic material on your bio Balls, the flow over them isn't good at all and would cause problems just like leaving a sponge or filter floss in too long.

On the other hand, if something dies in your tank, the Bio Balls act as a buffer to process the excess nutrient in the system.

Been running them in my overflow for three years and thought one day several months past that they had to come out for a look. They were clean, clean, clean. I put them right back in and still have no detectable nitrate to this day (Salifert).

[dmbnpj]

With this topic i should ask this? When should i replace the sponge and where to get a new one to fit?

Secondly, i have a small amount of aragonite/sand that has made its way down to the sump. Is this ok, or should i clean it as much as possible?

thanks,
jeff

[gillies]

If the sand isn't plugging anything up, leave it unless it bugs you. Replace the sponge when it begins to lose its shape or begins to fall apart. Remember, when you rinse it out don't try to kill it, just squeeze it gently under the tap until the gunk stops coming out. Any supply house online should carry a similar sponge you could cut to shape with a razor blade, or you might try filter floss.

[dmbnpj]

ive noticed little white bugs/critters in the drain portion of my tank. then the water passes thru this drain portion thru the sponge and into the return section of my sump.....so the bugs are trapped by the sponge. Are these the edible bugs that should be getting to my return portion to feed the fishies?

thanks

[gillies]

One valid argument about the limitaton of mechanical filtration - it can and will strain out potentially desireable creature like pods; however, the argument could be made that pods and such won't survuve the return trip to the main tank via the ferocious trip through the pump. You decide.