Dosing phosphate while running a refugium

[Potatohead]

How many people do this?

I was always under the impression it didn't make much sense, if you need more phosphate, either reduce your 'fuge lighting period or get rid of it altogether. However obviously there are other benefits to running a refugium, such as pH benefit at night time. Also at least in my setup running a 'fuge pretty much decimated all hair and turf algae in my display.

However my phosphate always tests very low, .01-.03 range. Nitrate is about 4-5. My corals are doing ok, although slow growing, a bit pale... They aren't thriving compared to other tanks I see. Polyp extension is quite limited comparatively. I have been trying to bring phosphate up to around .06-.08 for a long time, mainly by feeding more, but this has always led to other issues so I have scaled feeding back to 'normal.' I was doing some reading and a few reputable people mentioned algae (contrary to popular belief) seems to be fuelled more by nitrate than by phosphate. Mr. Balling himself was one of those people. So I started thinking dosing phosphate would allow me to increase it without also increasing organics and nitrate, which may be what my tank needs...

Thoughts and opinions welcome

 

[AllSignsPointToFish]

My personal opinion is that as long as you can control the phosphate in the 0.04-0.08ppm range, the worst thing that can happen is that you might need to harvest macroalgae from your refugium more often. My phosphate always runs in that range above...I couldn't get it down to your levels if I tried without either stopping feedings or using lanthanum chloride. I don't have an a nuisance algae problem at those phosphate levels, either, but my nitrates stay in the 1-3 ppm range.

 

[Potatohead]

Your numbers sound about where I'd like to be.

Can I ask how often you clean your glass? I need to clean mine every 4-5 days, and my chaeto grows very well and is very green. So I am not phosphate limited. I do get some of the pink algae on my sandbed, it's red like cyano, but it's dusty... Kind of weird stuff. So I have been hesitant to dose any phosphate because of those reasons, I don't seem limited. However my corals do look limited. So I wonder if I dose just a little it may help bring up phosphate, maybe bring down nitrate, and help reduce the red algae too (although this is more of a secondary thing to better coral health).

I guess I don't have much to lose in trying.

 

[AllSignsPointToFish]

I have to clean my glass once or twice a week. I think the nice part about dosing is that it would be pretty easy to stop it if the test doesn't give desired results.

Do you dose amino acids or carbohydrates? If not, I'd try that first. My corals were in the same boat as yours until I started the aminos/carbohydrates regimen.

What does your alkalinity run?

 

[Potatohead]

I have to clean my glass once or twice a week. I think the nice part about dosing is that it would be pretty easy to stop it if the test doesn't give desired results.

Do you dose amino acids or carbohydrates? If not, I'd try that first. My corals were in the same boat as yours until I started the aminos/carbohydrates regimen.

What does your alkalinity run?

I have tried dosing aminos many times. Tank just turns into algae explosion, even with 1/4 dose. Maybe I should be doing like 1/10 dose to start...?

Alk is consistent 7.7 - 7.9. Wouldn't mind it if dropped a bit more to be honest.

 

[AllSignsPointToFish]

My alk runs 7.9-8.1 which seems to be fine for the tank. The corals were not looking very good at an alkalinity of 10 even when I was dosing aminos/carbohydrates and all water parameters were good.

 

[Potatohead]

I still have like 80% full bottles of Fauna Marin aminos and foods I was using about six months ago. I'm going to go back in my notes and cut the dose I was doing by like 2/3 and try again. My corals did look better using them, but algae was worse too. I will try and find a happy medium. I do also suspect increasing my coral load will help too, but I have been hesitant to add more until I figure this out.

 

[Potatohead]

So for the last ten days or so I have been dosing a small amount of phosphate (.02) and testing daily. I was getting between about 18 and 24 consistently on the ULR which is about. 06, but I didn't see much change in the corals yet. Today I tested and got 37, which I thought was a bit high so I tested again but had to open a new reagent box to do so.

Test 0. Then 0. Then 2 ;Meh;Meh;Shifty;Shifty

Ugh.

So now I'm not really sure if the old reagents were crap or if the new reagents are. However I cleaned the glass on Friday and 48 hours later its still very clean, so I think it's still quite low. I set up the phosphate on my doser and am now dosing about .06 per day. May need to up that but I don't want to go crazy off the hop.

 

[Potatohead]

After posting last night I went and tested again. I used one vial I had used for the first test previously in the day, and got 57 ;Bored . This was the same vial I was getting readings of 18-24 with the last few days. Then I tested with a different vial I previously got 0 with that day, and got 8. This was after my doser had added a couple doses from previous testing, so that seems to make sense. So I think the reagents are ok but the one vial reading super high is messed up or, needs a good clean or something.

 

[Lasse]

Let it stand over night with citric acid. Rinse before use.

Sincerely Lasse