Help with phosphates

[bluecheese]

125 gallon tank with around 115 gallons of total water volume. Mixed reef.

Tank has been up and running since August of 2021.

I had surgery back in April. So I was not able to stay on top of the tank for 2 months while I recovered. I still did my weekly water changes and changed the filter socks. But I was not able to syphon out the sand like I normally would.

When I tested my water at the end of May on a Hannah checker, it came back as 1.94. Thinking I did something wrong, I checked again, and it came back at 1.84.

I started using GFO in a reactor at the beginning of June. I tested daily, and on June 18, the phosphates tested at 0.05.

I pulled the GFO, and the next day phosphates tested at 0.21. The day after that it was at 0.24.

On June 23 phosphates were at 0.39. So I started using GFO again.

The phosphate level slowly dropped to where I tested at 0.08 yesterday.

This morning it tested at 0.15 with GFO still in the reactor.

I test at the same time in the morning before the fish are fed. I feed sparingly. Change the filter socks out twice a week. I have a protein skimmer that is dialed in and produces a dark green skimmate that I clean out weekly.

Before surgery I would do weekly 10% water changes while syphoning out the sand. I have started doing the 10% water changes which includes syphoning out the sand since recovering.

I feel like my phosphate levels are like a bouncing ball, and I'm kind of sick of chasing numbers. I just want to keep it below 0.1 without having to constantly test and add/remove GFO based on test results.

Any ideas what might be going on?

 

[Randy Holmes-Farley]

I think the plan could be just use a much smaller amount of GFO all the time rather than turning it in and off. :)

 

[bluecheese]

I think the plan could be just use a much smaller amount of GFO all the time rather than turning it in and off. :)

Ok. I'm currently using 1/2 a cup. You think less would be better and just keep it going? Is there any concern about stripping out anything beneficial from the water?

 

[Randy Holmes-Farley]

Ok. I'm currently using 1/2 a cup. You think less would be better and just keep it going? Is there any concern about stripping out anything beneficial from the water?

There’s no way to remove phosphate without taking out some trace elements. The tank will appreciate more P stability.

A half cup should not drastically move the phosphate in a 125 gallon tank. How often were you replacing it?

 

[bluecheese]

There’s no way to remove phosphate without taking out some trace elements. The tank will appreciate more P stability.

A half cup should not drastically move the phosphate in a 125 gallon tank. How often were you replacing it?

I was replacing every 2-4 days or so.

 

[reefernc02]

What tester are you using for phosphate

 

[bluecheese]

What tester are you using for phosphate

Hanna phosphate checker.

 

[reefernc02]

How old is the testing agent I found it expires after a few months and starts to give mixed reading like it seems you’ve been receiving

 

[bluecheese]

How old is the testing agent I found it expires after a few months and starts to give mixed reading like it seems you’ve been receiving

Just bought a new box last week. Before that, the reagent was probably around 6 months old or so.

The reagent from the new box was used yesterday and today.

Both boxes have an expiration date of 2027.

 

[reefernc02]

Just checking I’ve found that the older it gets especially with the alk reagent and phos powder

 

[bluecheese]

Is there maybe reason to believe my rocks are leaching phosphate? I started the tank with dry marco rock. I'm just trying to figure out why my phosphates are so high recently when normally they are solidly below 0.1.

 

[p1u5h13r4m24]

What are you feeding? Dry food typically adds more phos

 

[p1u5h13r4m24]

Also protein skimmers are a huge factors for phos. Crank that baby up!

 

[reefernc02]

Is there maybe reason to believe my rocks are leaching phosphate? I started the tank with dry marco rock. I'm just trying to figure out why my phosphates are so high recently when normally they are solidly below 0.1.

It’s possible I feel like they biological filtration should’ve helped with that

 

[bluecheese]

What are you feeding? Dry food typically adds more phos

Mostly flake. But I've been feeding flakes for years with no issues. I feed sparingly, have good flow in the tank to keep the food suspended, and I change out the filter socks twice a week.

 

[bluecheese]

Also protein skimmers are a huge factors for phos. Crank that baby up!

Mine is cranked up. Collection cup has a good bit of dark green skimmate in it that I empty weekly.

 

[p1u5h13r4m24]

What are you feeding? Dry food typically adds more phos

Mostly flake. But I've been feeding flakes for years with no issues. I feed sparingly, have good flow in the tank to keep the food suspended, and I change out the filter socks twice a week.

I use reef roids sparingly when I want to raise phos. Consider switching to frozen and see if it helps?

 

[bluecheese]

It’s possible I feel like they biological filtration should’ve helped with that

I have ceramic balls as well as a Brightwell bio-brick in the sump.

 

[reefernc02]

Have you considered a algea scrubber I just got one from Josh at Clearwater scrubber’s and it’s wonderful quality

 

[bluecheese]

Have you considered a algea scrubber I just got one from Josh at Clearwater scrubber’s and it’s wonderful quality

I have. I need to see how much they cost. But space is at a premium under the tank. It sits on a custom made bookshelf. There is just enough room under there for the plumbing, sump, ATO bucket, and a dosing container.