Clear mucus Nitrate 0 Phos 0

[wheresmypistolshrimp]

I purchased a used reef tank almost a year ago, so live sand/rock were reused as well as water. The tank is a red sea reefer 350 (73 gal with 18 gal sump), I currently keep a pair of clownfish, midas blenny, one firefish goby, a small purple tang, 2 cleaner shrimp, 2 RBTAs, and some SPS corals. Since acquiring the tank, I was using red sea salt mix (blue bucket), and water parameters have been stable all this time with nitrates reading 10ppm and phosphates anywhere 0.10 to 0.15. Given that I have some SPS, I had been working on reducing my phos levels so about 1 month ago, I decided to add rowaphos in a media bag which I placed in the sump. I also switched to reef crystals (orange bucket) at that same time. A week ago during a water change, I noticed my nitrate was at 5ppm and noted some clear thick mucus in the sump that had clogged my filter socks. I didn't think much of it until now. I did a water change yesterday, and today my filter socks are clogged with clear mucus again, which is now starting to show up in my main tank. In researching previous posts, it looks like a bacterial bloom that happens when a tank is nutrient deficient after carbon dosing. I have not treated the tank with any chemicals other than adding the rowaphos 1 month ago, changing sea salt brands, and I also keep activated carbon in a media bag in the sump.

Could any of these changes have contributed to the sudden drop in nutrients and mucus bloom? I would appreciate any recs. Should I remove carbon/GFO? I have changed the position of the return T-pipes to increase water surface aeration and increased feedings. I plan to reduce my water change schedule which was 10% every week.
Current parameters:
Temp:76-77.5
pH=8.0
Nitrate=0
Phosphate=0
dKH=8.2

 

[Timfish]

It's good you're feeding your fish more. I would continue doing your water changes and using GAC. Both will help lower DOC in your system although GAC is a bit selective where water changes reduces everything. FWIW phosphate levels 0f .15 mg/l are fine ( .03 mg/l to .5 mg/l). You mentioned adding labile DOC (cabon dosing), I'd stop that as it's impossible to say what bacteria it will promote and may very well be the cause of the increased biofilms. Keep in mind we are dealing with particulate and dissolved organic forms of nitrogen and phosphorus as well as the inorganic forms you've been testing for, reducing PO4 and NO3 to untedectable levels shifts how nutreints are being processed but doen't mean there isn't any ntrogen or phosphorus in the system.

 

[wheresmypistolshrimp]

It's good you're feeding your fish more. I would continue doing your water changes and using GAC. Both will help lower DOC in your system although GAC is a bit selective where water changes reduces everything. FWIW phosphate levels 0f .15 mg/l are fine ( .03 mg/l to .5 mg/l). You mentioned adding labile DOC (cabon dosing), I'd stop that as it's impossible to say what bacteria it will promote and may very well be the cause of the increased biofilms. Keep in mind we are dealing with particulate and dissolved organic forms of nitrogen and phosphorus as well as the inorganic forms you've been testing for, reducing PO4 and NO3 to untedectable levels shifts how nutreints are being processed but doen't mean there isn't any ntrogen or phosphorus in the system.

Thank you for your response. I meant, I’m NOT dosing any carbon other than having added the GAC in a media bag and rowaphos. So keep GAC in sump. Should I remove the rowaphos? Also, should I switch back to Red Sea salt mix?

 

[Timfish]

Thank you for your response. I meant, I’m NOT dosing any carbon other than having added the GAC in a media bag and rowaphos. So keep GAC in sump. Should I remove the rowaphos? Also, should I switch back to Red Sea salt mix?

Carbona dosing is very different from GAC. It's adding a labile dissolved organic carbon product to a system to promote microbial growth and can promote pathogenic microbial shifts in coral microbiomes. Yes, remove the rowaphos, you want to raise your phosphates. The link I refferences the .03 mg/l is research done over about a decade by researchers at Southampton Univeristy in England showing that to be a minimum threshold to assure corals aren't phosphate limited.

 

[wheresmypistolshrimp]

Thank you all. So all this mucus appeared over the course of two days to the point where my filter sock kept clogging and water over flowing. I didn’t want to do anything too drastic so I started with increased feeding. After two days, it disappeared and the same clogged filter sock cleared up and it’s flowing fine now. There are some minimal strands left around, but it seems like everything has mostly cleared up. I’m still getting Nitrate and Phos readings of 0. Working on getting a different test kit to confirm. I think it might be accurate as I’ve seen some of the glass algae disappear.