Should I start dosing nitrates?

[Christopher Carey]

My tank is a little over a year old...130 gallon with 40 gallon sump (refugium with Chaeto and Red Ogo algae on reverse light cycle from display lights). I seem to be having issues keeping nitrates up (they are detectable, about 0.25 ppm by Red Sea test kit) and I suspect low nutrients are causing issues with being able to keep SPS alive longer than a few weeks to a month.

Full tank parameters:
Alk: 7.4-7.5 (maintained with auto dose at 22mL per day)
Calc: 420-430 (maintained with auto dose at 22mL per day)
Mag: 1350-1380
SG: 1.0255
pH: 8.07-8.2 (over 24 hours on average)
Temp: 78
Nitrate: 0.25 on average (has been as low as undetectable or very faintly pink about a month ago)
Phosphate: 0.10 on average

Livestock as follows: Yellow Tang, Blue Tang, Kole Tang, Percula Clowns (2), Dispar Anthias (3), Black Axil Chromis (3), Midas Blenny, Sixline Wrasse, Yasha Gobies (2), Lawnmower Blenny for a total of 16 fish. I feed what seems to be fairly heavily (2-3 cubes of frozen twice a day), as well as dose Phytoplankton daily. I add Reef Roids once a week as well (target feeding).

I was having issues with algae (mostly turf and a bit of hair algae) on most of the rock in the display as recently as a month ago, but adding a LOT of snails, a Tuxedo Urchin and the lawnmower blenny have reduced the algae significantly. Photos posted for reference (please forgive the terrible iPhone quality).

A few months ago (and for quite a few months) I was dealing with the same algae issues and a LOT of it, which I suspected was from heavy feeding in an attempt to get nutrients up. However, this likely just fueled more algae growth and kept nutrients extremely low. At that time I attempted to dose nitrates (NeoNitro) to at least achieve detectable levels, while maintaining phosphates above 0.10, but I noticed some pretty negative responses from multiple corals (a few different LPS and SPS) while dosing nitrates over the course of a few weeks. A few months prior to that, I attempted to dose nitrates for the same reasons, instead using a Loudwolf product (Potassium Nitrate), but experienced much of the same effects. Those experiences are why I'm hesitant to just start dosing nitrates again, but would like to give myself more of a buffer from bottoming out.

Any help you all can provide is greatly appreciated. I also posted my latest Triton test for reference (which doesn't seem to point out anything out of the ordinary).

 

[dwest]

I’m surprised that your tank responded negatively to addition of either nitrate product. Both should be fine. But if you have some nitrates, I doubt nitrate levels are the problem. Other tank parameters look good. I would make sure to dose alkalinity slowly throughout the day If possible.

I see some acros in there. If they are holding on, I would just be patient. What is your lighting and flow?

 

[dwest]

Just noticed some nice coralline algae in there also. That’s a good sign.

 

[Christopher Carey]

I’m surprised that your tank responded negatively to addition of either nitrate product. Both should be fine. But if you have some nitrates, I doubt nitrate levels are the problem. Other tank parameters look good. I would make sure to dose alkalinity slowly throughout the day If possible.

I see some acros in there. If they are holding on, I would just be patient. What is your lighting and flow?

I spread the alkalinity dose over 2 doses (11mL each dose spread out over 3 hours each dose). However, both doses occur during lights out (0000-0300 and 0600-0900 on Apex), which my thought process here was to have the alkalinity dose also help buffer the pH drop during lights out. Calcium is dosed in 2 doses (11mL each spread out over 3 hours each dose) and occurs in the afternoon and evening (1200-1500 and 1800-2100). However, I'm thinking about adjusting to 4 doses spread out throughout the day, with Calcium dosed in between in 4 equal doses as well (yet separated by 30 minutes at each starting dose).

My lighting setup is 2x EcoTech Radion XR30 at 54% and mounted 9" off water along with an AquaticLife hybrid fixture with 4x T5 bulbs (2x Blue Plus and 2x Actinic)...the T5s are on 100% for about 4 hours at peak. Total lighting period is 11 hours, with a 4 hour peak mid-day where the Radions are 54% and the T5s are 100%). Flow is provided by 2x Maxspect Gyre 250s at top on each side, as well as 2x Maxspect Gyre 230s mounted mid-way vertically in the back of the tank.