Low nitrate, exceptionally high phosphate

[Nor'easter Reefer]

So, I don't have any corals yet. That's in the immediate future but I want to figure out/manage this issue first as my end goal is sps dominant.

Nitrate:4.8
Phosphate:>.90 (hanna ulr max limit)

I assume, it's to do with the 6 months I didn't have a skimmer, and didn't do a lot of water changes. That said I had a refugium running lights opposite to my display tank and was getting decent growth. I have a old phosban reactor kicking around somewhere from my first tank 8+ years ago. I was thinking about getting some gfo and brining my phosphates down, and then either disconnecting the reactor, or (if it's advisable) putting it on a timer for a few hours here and there, and watching to see how long it takes/if it creeps back up? I'm having a decent bought with cyano right now so I'm just trying to figure this out before I get any corals.
I have another powerhead arriving tomorrow so I can get some more flow going into one spot that seems like a low flow spot, I've been doing approximately 15% water changes and vacuuming small sections of the sand bed the last month or 2(just finished the last section so am at 100% sand bed cleaning, but just tested my phosphates the other night as my reagents showed up for my tester and my other test kit was hard to read.
120g display with approximately 45g sump.
Dry rock, dry sand, bright well nitrifying bacteria starter kit, started in around may. Thanks!

 

[rishma]

There are lots of good ways to keep a tank. I would say an SPS dominant tank without a skimmer is not typical. Do you plan to get a skimmer?

I think GFO is a tool that will help your current situation. You can test the outlet of your reactor to know when it’s getting depleted. At those high phosphates, you will have a lot to remove as it is released from the rocks. Slow and steady will be more sustainable. If you strip the tank water quickly then turn off the GFO , PO4 will rise again as it’s released from the rocks. To avoid this yo-yo, I prefer smaller GFO amounts and patience.

 

[Nor'easter Reefer]

There are lots of good ways to keep a tank. I would say an SPS dominant tank without a skimmer is not typical. Do you plan to get a skimmer?

I think GFO is a tool that will help your current situation. You can test the outlet of your reactor to know when it’s getting depleted. At those high phosphates, you will have a lot to remove as it is released from the rocks. Slow and steady will be more sustainable. If you strip the tank water quickly then turn off the GFO , PO4 will rise again as it’s released from the rocks. To avoid this yo-yo, I prefer smaller GFO amounts and patience.

I picked up a reef octopus around black Friday, unfortunately that won't help get my phosphates down rather prevent it from accumulating like it has correct? I still need to pull it out. So I planned to use gfo in a reactor at like... 1/2 the recommended dose for starters and see where that gets me?

 

[rishma]

I picked up a reef octopus around black Friday, unfortunately that won't help get my phosphates down rather prevent it from accumulating like it has correct? I still need to pull it out. So I planned to use gfo in a reactor at like... 1/2 the recommended dose for starters and see where that gets me?

Correct the skimmer will not remove the phosphate directly.

Starting with half recommended amount of GFO is never a bad idea. Given that you have no corals and your phosphate is quite high, I’d personally start with the recommended amount, but no harm in starting slower.

 

[Nor'easter Reefer]

Correct the skimmer will not remove the phosphate directly.

Starting with half recommended amount of GFO is never a bad idea. Given that you have no corals and your phosphate is quite high, I’d personally start with the recommended amount, but no harm in starting slower.

Full strength because there's no corals to shock and fish won't care? I'm worried about drastic swings cause issues with my cyano situation

 

[rishma]

Full strength because there's no corals to shock and fish won't care? I'm worried about drastic swings cause issues with my cyano situation

I don’t think fish care. I also don’t know that it will be a shock given how high your phosphates are.

The problem people run into is stripping phosphate out of the water too low, too fast. Then removing GFO because corals are stressed, then phosphate spikes back up. Yo-yo.

There is zero downside in my opinion to using a smaller amount. You can add more later.

In order to sustainably keep your phosphate low, i think you’ll need to run some longer term to remove the phosphate from the rock

 

[Nor'easter Reefer]

I don’t think fish care. I also don’t know that it will be a shock given how high your phosphates are.

The problem people run into is stripping phosphate out of the water too low, too fast. Then removing GFO because corals are stressed, then phosphate spikes back up. Yo-yo.

There is zero downside in my opinion to using a smaller amount. You can add more later.

In order to sustainably keep your phosphate low, i think you’ll need to run some longer term to remove the phosphate from the rock

Awesome. That's kind of what i thought, nice to have some confirmation. Thanks!