Bubble trap sponge - needed?

[clhardy5]

I have a RR525xl - 108 gallon dt....39 gallon sump. It has been up and running for almost 4 months, and things are going well - except - I can't get my nitrates to go below 20ppm.

In the sump, I have 2 filter socks, a skimmer, 1 biobrick, 1 gallon of murine pure bioballs, and a refugium - growing chaeto like its a weed... I also have a large bubble trap sponge - as per the manufacturers design - just before the return pump. The sponge is really nasty, and I'm wondering if it is part of the cause of my nitrate issue. I have a very healthy pod population (I also cultivate in a separate setup for my mandarin) - and I know some of the pods have taken up home in the sponge. So....my question is......would it be ok to remove the sponge - slowly - in bits of course - or would I really affect my pod population - or anything else the I'm not considering.

I've tried removing half the sponge, and rinsing in RO - and putting it back - but so far that hasn't had too much of an effect on nitrates.

I've run Purigen in my 32 gallon biocube in the past.....would that help with the nitrate issue in my 525XL?

I don't think I overfeed, and my skimmer is doing its job. - pulling out nasty dark brown crap.....and I change my filter socks every 2-3 days. Short of MORE water changes (I do 10% a week)....what else should I consider or do for my nitrate issue?

Newbie looking for answers - I can take advice and criticism - so I'm open to suggestions.

 

[vetteguy53081]

Pictures of what you’re referring to would be helpful

 

[clhardy5]

Pictures of what you’re referring to would be helpful

Sorry...I was going to wait until the fuge light came on....but here you go. I'm talking about the black sponge thing between the pieces of glass - to the right is the fuge (Chaeto), and to the left is the return pump.

 

[vetteguy53081]

Ok- gotcha. I confused myself
Mix a small batch of seawater and test it to see if it’s from your salt mix. Also test the RO water for nitrates
What test kits are you using ?

you may have better luck using chemipure blue OR Elite

 

[clhardy5]

Ok- gotcha. I confused myself
Mix a small batch of seawater and test it to see if it’s from your salt mix. Also test the RO water for nitrates
What test kits are you using ?

you may have better luck using chemipure blue OR Elite

RO water and Saltwater didn't have any detectable nitrates. I am using Salifert.

Just ordered some Chemipure elite. It gets here Saturday. I'll see what happens. For now, I'll leave the sponge in....I'm sure the pods will appreciate it.

 

[mfinn]

I use a sponge in my sump too. I usually just pull it and rinse it in tap water. Once it gets too dirty to clean, I replace it.
I buy the hang-on back filter large sponges off amazon when I run out of the bigger bags of them sold on ebay.
They are larger than the opening so I have to cut them down to the right size.