Low Nitrates / High Phosphates

[Trouble1375]

Details - tank is 2 years old mixed reef. 125 gallons with dual sumps. One sump has chaeto (lighted 9 hours opposite the DT), live rock, shrimp, hermit crabs and snails that find their way from the display. The shrimp and hermits are intentional. The other sump has a roller mat. Both have an overflow from the tank and at return pump. We have a water bridge to maintain the same water level in both sumps. We have 20ish fish, nearing 60 frags/mini colonies, a large meat coral, good size Lobo and trachy and a nice plate coral. The tank has never grown coralline algae.

Parameters as of 5/16/21:
Temp 77.9
Salinity 1.025
pH 7.9
Calcium 489
Magnesium 1280
Alk 9.072
Nitrate 2.41
Phosphate 0.14
Iodine 0.6
Strontium 0 - tank seems to be using alot of Strontium

ATI Essentials PRO through auto doser, Kalkwasser also automated, just added magnesium to auto dosing schedule. ATO adds about 2 gallons of RO/DI daily (this is where the Iodine and Strontium are dosed from). RO/DI is tested @ 0 TDS.

Feeding 5 cubes frozen daily, 1/4 sheet of Nori. Twice a week Red Sea AB+, Reef Roids once a week, Phyto and Zooplankton 3 times a week.

The chaeto is new - just switched over from an ATS that we took offline over a week ago.

The Phosphates won't drop and we can't get the nitrates to increase. We don't like chemical options but if we must resort to them we will. What is the best option to increase the nitrates while decreasing the phosphates. I know Redfield Ratio says they should be 16:1 and we are not near that ratio.

 

[IslandLifeReef]

Details - tank is 2 years old mixed reef. 125 gallons with dual sumps. One sump has chaeto (lighted 9 hours opposite the DT), live rock, shrimp, hermit crabs and snails that find their way from the display. The shrimp and hermits are intentional. The other sump has a roller mat. Both have an overflow from the tank and at return pump. We have a water bridge to maintain the same water level in both sumps. We have 20ish fish, nearing 60 frags/mini colonies, a large meat coral, good size Lobo and trachy and a nice plate coral. The tank has never grown coralline algae.

Parameters as of 5/16/21:
Temp 77.9
Salinity 1.025
pH 7.9
Calcium 489
Magnesium 1280
Alk 9.072
Nitrate 2.41
Phosphate 0.14
Iodine 0.6
Strontium 0 - tank seems to be using alot of Strontium

ATI Essentials PRO through auto doser, Kalkwasser also automated, just added magnesium to auto dosing schedule. ATO adds about 2 gallons of RO/DI daily (this is where the Iodine and Strontium are dosed from). RO/DI is tested @ 0 TDS.

Feeding 5 cubes frozen daily, 1/4 sheet of Nori. Twice a week Red Sea AB+, Reef Roids once a week, Phyto and Zooplankton 3 times a week.

The chaeto is new - just switched over from an ATS that we took offline over a week ago.

The Phosphates won't drop and we can't get the nitrates to increase. We don't like chemical options but if we must resort to them we will. What is the best option to increase the nitrates while decreasing the phosphates. I know Redfield Ratio says they should be 16:1 and we are not near that ratio.

First question, does everything seem happy and healthy in your tank?

If the answer to that question is yes, then why are you chasing numbers? The goal of a reef tank is to grow happy, healthy corals and keep happy fish. If that is being accomplished, I would keep my numbers where they are.

The redfield ratio really isn't useful when trying to maintain a balance in your water because that ratio has nothing to do with water. What I have found is my tank is happiest when NO3 is 10-50X higher than PO4. Now I know that is anecdotal, but it is probably more useful than the redfield ratio.

 

[Randy Holmes-Farley]

Those values seem OK to me.

The Redfield ratio should not be misinterpreted as a nitrate or phosphate concentration goal.

 

[Daniel]

No coralline seems weird... pics would help. Corals and other livestock seem happy?

But agree with comments above, values seem OK to me.

A side question, have you noticed the Chaeto growing well? It seems you mentioned it's new, did the previous batch die off?

It wasn't until my chaeto was able to stay alive and really took off that I noticed my phosphate numbers getting under the 0.15 mark. It now hovers around 0.05-0.08 with no major adjustments to feeding / water change / nutrient export - except for the growth in Chaeto. To get it to take off, I had to up my dosing of Chaetogro on a dosing pump for consistency.

Good luck!