Nitrogen Bound Tank? - Dosing nitrates to lower phosphates?

[305Reefer]

My tank:

90g Aqueon 48x18x24 Mixed Reef - LPS/Softie Dominate with a few SPS.
35g Trigger Sump
30g Deep Blue Frag Tank 24x24x12
Total Actual Water Volume: Apprx 120g

1.026SG
1 Nitrate
420 Calcium
1350 Magnesium
8dKH Alkalinity
Phosphates swing like mad between .01 and .1

Tank has a big skimmer and a refugium lit with a 300w Grow Spectrum LED Lamp.

So my question is about nutrient removal from my tank. This tank was a pre-established system but Ive only had it for 5 months. Its probably 2 years old overall. I feed it pretty normal for my bioload and since I have had it Ive never been able to get nitrates above 1ppm. My goal was to get 3-5ppm to color up some SPS. My phosphates however have always swung up from time to time. Usually coinciding with me feeding extra heavy for a couple weeks at a time. Doing so would bring me from .03 to .1 on a regular basis. I would bring this down using a 20% water change (usually done every 2 weeks) and/or by using a tiny tiny bit of GFO which brings it down really fast, even when its just a couple table spoons. For the most part it works great just the way it sits, corals are growing super fast, look great, etc.. When the phosphates climb up above .06 I start to notice the glass gets dirty faster and I'll see small sections of surface algae look "Fuzzier" than normal.

So! Regarding my refugium. It seems to pull nitrates out of the water like no one's business. No matter how heavy I feed I can never get my nitrates up above .5-1ppm. But it can't seem to pull phosphates out of the water for the life of it. I was reading up a little about Chaeto but it was a bit over my head and I got confused.

Am I right to assume that chaeto for the most part pulls more nitrate then phosphate out of the tank, and cant pull more phosphate out of the tank without their being a better nitrogen (nitrate) source?

If I dosed spectracide stump remover to bring my nitrate level up would I in turn give my fuge the fuel it needs to remove more phosphates out of the tank? Is this wise or should I just stick to using the occassional GFO.

Picture of my setup for fun.

 

[Ashish Patel]

Your tank seems to be doing good at low nitrates. If you start dosing Nitrates you could possibly give nuisance algae fuel to grow. Embrace your low nutrients numbers they will gradually increase as your tank ages. My nitrates stay at .2-.5 and I have learned as long as they are stable and not 0 don't stress it. I think you nitrates are perfect and there is a difference in having low nutrients as would be in new salt instead of low nutrients in a well stocked tank.. High nutrient in and high nutrient out is the goal IMO.

 

[Ashish Patel]

BTW good job on the aquascape!! did you use the caribsea shapes rock?

 

[Ashish Patel]

And to answer you question I don't think if you add nitrates your cheato will have more fuel to remove PO. My phosphates did the same thing first 5 months (.01-.08)while my nitrates stayed the same. I thought this was normal but now I've tested PO 8 times in the past 2 month and get it around .03 (regardless of feeding). I think the tank matures eventually with phosphates perhaps it has something to do with hobbyist tinkering less with flow, lighting and skimmer. Since when I finally stopped messing with stuff the tank stabilized to rock solid parameters. I had a bad experience dosing nitrates and looking back its better to just reduce your light intensity and Alk. Which I found helped tackle the low nitrates and phosphates. Anyways hope this helps!

 

[305Reefer]

And to answer you question I don't think if you add nitrates your cheato will have more fuel to remove PO. My phosphates did the same thing first 5 months (.01-.08)while my nitrates stayed the same. I thought this was normal but now I've tested PO 8 times in the past 2 month and get it around .03 (regardless of feeding). I think the tank matures eventually with phosphates perhaps it has something to do with hobbyist tinkering less with flow, lighting and skimmer. Since when I finally stopped messing with stuff the tank stabilized to rock solid parameters. I had a bad experience dosing nitrates and looking back its better to just reduce your light intensity and Alk. Which I found helped tackle the low nitrates and phosphates. Anyways hope this helps!

Thanks a lot. Good insight. This may be happening now to my tank as I have noticed my problems have been slowing down and certainly my uptake of alkalinity has stabilized.. I used to have to adjust it from 40ml to 45ml and back every other week as it would drift from 7.9 to 8.3.. Lately its been locked at 8dKH with 45ml of 2-Part. Luckily ive never gotten nuisance algae except in my sump so far..

As far as the aquascape goes you are correct, that's the Caribbsea Shapes Rock. Good stuff. The 30g has brand new rock. The 90g has the old rock covered in coralline, sponges, tunicates, brittle stars, bristle worms, etc.

 

[Randy Holmes-Farley Verified Community Expert]

IMO, 0.5-1 ppm nitrate is fine, but dosing some would be a fine experiment to see how the tank responded.

 

[chefjpaul]

Put some more fish in those beautiful tanks.

 

[Ashish Patel]

Thanks a lot. Good insight. This may be happening now to my tank as I have noticed my problems have been slowing down and certainly my uptake of alkalinity has stabilized.. I used to have to adjust it from 40ml to 45ml and back every other week as it would drift from 7.9 to 8.3.. Lately its been locked at 8dKH with 45ml of 2-Part. Luckily ive never gotten nuisance algae except in my sump so far..

As far as the aquascape goes you are correct, that's the Caribbsea Shapes Rock. Good stuff. The 30g has brand new rock. The 90g has the old rock covered in coralline, sponges, tunicates, brittle stars, bristle worms, etc.

Nice, I was considering ordering a box I see BRS has a box for $84, but talked myself out of it since I really don't need it. Seeing how impressive your scape looks might just have to relocate some rock to the sump and add this.
Thats strange on your ALK consumption make sure you test everyday at the same time. You'd be surprised to find how much it swings even with continous dosing. I've seen it swing easily .2-.4 DKH per day which is fine since its just normal fluctuation. Don't go chasing nitrate numbers your tank looks like it has plenty of nitrates, Just feed or add few more fish.