Amount of PO4 from frozen foods, pellets, nori?

[ACBlinky]

I'm wondering if anyone knows how much phosphate gets added to a tank when we feed certain foods. My phosphates are out of control (1.3ppm) despite chaeto and caulerpa that grow well. It's not the source water, I tested it last night and it's at 0.0ppm (Hanna checker).

It has to be the foods I'm feeding. Here's my problem - I have fish that want HUGE amounts of nori, they can't seem to get enough. When they've finished what I give them, they return to the clip over and over, and beg at the glass like dogs for more.

So... let's say I feed a half-sheet of nori, about 4" x 8", and two cubes of frozen food in a day. The frozen food disappears immediately, the nori lasts about an hour if I'm lucky. How much PO4 did I just add to ~150g of water? (150g tank + ~25g sump - rockwork)

Has anyone done this kind of phosphate math? If there's a formula, I'd love to see it, even though I'm sure it'll make me bang my head against the wall

[aandfsoccr04]

Basec on no science or evidence, I sincerely doubt it's the food that is causing your problem. I remember Randy saying that it isn't even worth it to rinse the food before you feed it to your tank because the phosphates are so few.

[ACBlinky]

Really? I'd love to know what I'm doing wrong... what are the things that add PO4 to our tanks, other than foods?

[ACBlinky]

Ugh. Just did some reading, and I'm wondering if my rock is the issue. I used mostly base rock, and it's entirely possible it was just loaded with PO4.

My plan for today is to conduct a fairly large water change, siphon debris from the sump, harvest some of the macroalgae and add PO4 adsorbing resin. *Fingers crossed*

[Patroklos]

If you think its your rock pull out a piece and put into a bucket of RO water you tested to be 0.0. Let it sit in there with a powerhead for a week and then test and see what happens.

[Palting]

IMO, phosphates are ever present in nature. It's in the DNA, literally and figuratively. So, no matter what you feed that comes from nature and has DNA, there will be phosphates.

It just comes down to how to deal with it. Large refugium with macro's trimmed frequently, ATS, water changes frequently, GFO..........

Just IMO.

[t4zalews]

Based on your signature, you have a remora for a skimmer? That should def be upgraded for a 150g. And sounds like you have heavy waste fish if they keep chowing nori, so I would def upgrade your skimmer

[ACBlinky]

a skimmer upgrade is definitely planned for the future, but there's not a lot in the reef budget at the moment.

Would it be better to get a phosphate reactor and GFO now, or put the money towards a better skimmer and continue to use resin in the HOB for now? I'm going to be using Phosban; when that runs out, I want to switch to GFO.

I'm also going to stop using carbon, for two reasons - it doesn't seem to do much, and everything I read indicates that it can be a significant PO4 source. I may be doing more harm than good by running carbon 90% of the time :S

Just goes to show how much I still have to learn; every new problem I run into teaches me something else! This is an endlessly educating hobby

[Squidmotron]

It's actually good news if it is your rock IMO. My experience is it releases fewer and fewer phosphates over time.

GFO reactors are a really pretty cheap. Maybe try that (start with a small amount) while saving for your nice skimmer.

Do you have space where you can create a little refugium? There's another phosphate export idea.

[t4zalews]

I've never heard of carbon being a po4 source. But for your purposes, GFO will be more beneficial. I'd look for skimmer on here for a discount. Any in sump skimmer is going to better than the remora.

[Palting]

I've never heard of carbon being a phosphate source, either, and I run it 24/7 on account of having a mixed reef. Agree on GFO, in a reactor, to be one of the good things for phosphate removal.