can you carbon dose with no phosphate?

eddiereefs

New member
hey guys like the title says i have been carbon doseing for a little of a week to battle high nitrates, however since i have been running gfo i am reading zero phosphate on an api test (i know not a good one) do u think it is a testing error or that it is true. i know carbon doesing in better for nitrate reduction which is why i went this route but its been 8 days and my skimmate production remains the same. too soon to tell or not gunna happen. please help

eddie reefs
 

Breadman03

New Old School
Premium Member
Nope. You need all three present to be effective. Also, carbon dosing generally isn't useful for lowering high nitrates, but is very useful for maintaining them at a low level.
 

tkeracer619

Premium Member
Large water changes for nitrate reduction.

2 50% water changes will drop your nitrates to 20ppm.

You will most likely be phosphate limited but I doubt it is actually zero.
 

reefgeezer

New member
After 8 days you should be at a very low dose. Nitrate reduction will occur after you've built up to an effective dosage, but you can't be impatient.

It is true that nitrate reduction can be limited by a lack of phosphate... but... Almost any hobby grade test kit will read zero when phosphate is easily high enough to allow nitrate reduction. Other circumstances can also make test kits wrongly report low readings.

You might tell what/how much you are dosing, what skimmer you are using, how big the tank is, the bioload, how high your nitrates are, if you have hair algae, etc. That would help.
 

eddiereefs

New member
Thanks guys, i know that i do have phosphates because i have some bryopsis that is consuming it. So i know vodka dosing will work. Its a 29 gallon im dosing .70 ml as per suggestion. I am using an eshopps psk75. I am also running gfo. Its a month old i cant see it lowering any more phosphates. I have already seen a little bit of nitrate drop. Nitrates are at 40ppm only have 3 fish and 4 corals.
 

ReefsandGeeks

New member
You're tank has only been running for a month? Seems kind of early for coral IMO. Though I waited untill my system was very stable and had pristine water before adding coral to mine. I don't know how soon exactly is too soon. I'm assuming since your tank is so new that it has just finished cycling very recently, and that's why you have such nigh nitrates. If that's the case, I'd take tkeracer's advice on the water changes to get the numbers reasonable quicker, then use a dose of vodka and patiance to lower them further and maintain them low. Being a new tank you woun't have much extra bacteria colonies, so it could take a little extra time to get them built up to reduce your nitrates.
 

ReefsandGeeks

New member
also +1 on test kits for phosphate not being the best. I've heard the API one is a high range scale, and not very useful for a reef? not sure on that. What are the scale increments?

If you have algae, you have phosphates. If the water itself had absolutly no phosphates, you can still have algae, but it can't grow, and would likely slowly deteriorate. I belive that even the good hobby test kits can read 0 even when there is still enough phosphate to allow some algae.
 

SGT_York

New member
And an API test starts showing results at .25 which is already past the point of inhibited stony coral growth. It's a good test for FOWLR, get a better phosphate test. You need to be testing at the .02 range not .25.
 
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