Phosphate confusion

Johnny bass07 · Jan 22, 2020

I have been dosing neophos trying to raise my phosphates and I have not been able to get them over 0.40. I checked them earlier and it was 0.037 so I dosed 2 ml and checked it an hour later and it went down to 0.028. It went down instead of up. I use a hanna checker ulr with new reagents. I'm confused!

Whiskyclown · Jan 22, 2020

Johnny bass07 said:
I have been dosing neophos trying to raise my phosphates and I have not been able to get them over 0.40. I checked them earlier and it was 0.037 so I dosed 2 ml and checked it an hour later and it went down to 0.028. It went down instead of up. I use a hanna checker ulr with new reagents. I'm confused!

Why would you want your phos. High ???

Whiskyclown · Jan 22, 2020

Whiskyclown said:
Why would you want your phos. High ???

What test kit you using

C. Eymann · Jan 22, 2020

What are you using to test? if hanna, are you sure you are getting every last grain of reagent into the curvette? it loves hiding in those corners of the packets.

My guess is test error

Larry L · Jan 22, 2020

You're trying to distinguish between numbers that are within the margin of error for the checker. The Hanna ULR phosphate checker has an advertised accuracy of ±0.02 ppm ±5% of reading, so a reading of 0.037 ppm could mean an actual value in your tank anywhere from 0.015 ppm to 0.059 ppm.

I have an error range calculator at: http://larryl.emailplus.org/fish/test-kit-calculators.html

Terri Caton · Jan 22, 2020

Larry L said:
You're trying to distinguish between numbers that are within the margin of error for the checker. The Hanna ULR phosphate checker has an advertised accuracy of ±0.02 ppm ±5% of reading, so a reading of 0.037 ppm could mean an actual value in your tank anywhere from 0.015 ppm to 0.059 ppm.

I have an error range calculator at: http://larryl.emailplus.org/fish/test-kit-calculators.html

Hey Denver! That's a great link thanks.

Larry L · Jan 22, 2020

Terri Caton said:
Hey Denver!

Hey back! Are you going to be at ReefStock? If so, look me up, I'll be helping Jake with things at the show.

Johnny bass07 · Jan 22, 2020

I feel after dosing 2ml it shouldn't go down. My alk is high and burning tips so trying to get phosphates and nitrates up until I can get alk down. Using hanna checker ulr

Randy Holmes-Farley · Jan 22, 2020

Johnny bass07 said:
I feel after dosing 2ml it shouldn't go down. My alk is high and burning tips so trying to get phosphates and nitrates up until I can get alk down. Using hanna checker ulr

Most of what you dose will end up bound to rock and sand. If you want phosphate to rise by, say, 0.03 ppm, you might end up having to dose ten times that amount.

Johnny bass07 · Jan 22, 2020

I don't have sand but I do have a lot of live rock. If it bounds to the rock will it cause problems leaking later on?

Worthy1 · Jan 22, 2020

As Randy mentioned, phosphate consumption can be a number of things and it will change from time to time, this means your dosage needs will change from time to time.

My tank is about 9months old and my phosphates have been at 0 which is causing an algae outbreak and halted my sps growth I was starting to see. I bought some trisodium phosphate but unfortunately working out the correct mix has been hard. Because I cant test how much phosphate the main solution has (Hannah checker only goes to 2.5), I overdosed the tank. My phosphates went to 2.34! what was crazy about this is there was no adverse effect on my sps frags or the fish. After a water change I managed to get them down to 1.6. Still way to high but as it was not affecting anything I decided to see how much phosphates my tank currently consumes every 24hours. My tank consumes .12ppm every 24hrs and I am now down to .14ppm. So I need to take that into account when I work out dosing.

My point to my long story is you need to baseline your consumption, then you can work out how much to dose.