Phosphate Problems + Hanna Checker Question

[dbjonesjr]

Hi all. I’ve been looking to get into some more SPS (than the Chili Pepper Monti and Purple Monti Digitata I currently keep) so as a result I’ve been keeping better track of phosphates. Come to find out (after picking up a Hanna H713 from a fellow reefer with new reagents for $20!) I have been reading my Salifert kit at lower values than actual. I figured I was pretty close to .03 with the Salifert kit. Hanna is reading around .09 to .14. Will explain the variance in a second. Anyways now to my actual problem and a follow up question.
Tank Information - in the middle of moving to an all out 90G build, trying to get problems solved first
Size: 40G
Light: T-247B
Filtration: No sump on this one
Rock: 25 lbs Pukani, 35 lbs BRS
Sand: Maybe 1/2” to 1”
Feeding: 1 cube mysis 5 days/week (and reef chili per instructions about 2 days/week)
Alk: 9-10 dKH
Calc: 450 ppm
Mag: 1500-1600 ppm
Nitrate: 0 ppm (API/Salifert, have considered dosing)
Phosphate: as described
I started running Phosguard after learning my phosphate was higher than I would like at .14 ppm. Initially it didn’t do much (older stuff had been in the reactor without water for about a month or two) so refilled it with new media. Got my phosphates down to .09 overnight (this was tested yesterday morning). When checked last night my results were .10. Stopped running the reactor (have read about phosphates being leached back in from the media after it is saturated). Checked this morning and got .12 on the Hanna with the Hanna reagents. Now on to a couple of my actual questions.
As I didn’t feed between last night and this morning is it possible that my rocks are leaching phosphate back in? Or is it likely just food that is continuously being broken down?
As a test out of curiosity I used Salifert phosphate reagents in the Hanna checker. I got .14 vs .12. Is it possible to use up my Salifert reagents in the Hanna (to get my $20 out of it). I figure at this range it probably wouldn’t hurt to use it till I can finally get them down to my goal of around .05.

 

[RobZilla04]

Phosphate is fine at .03, .09, and even .14

You'll never be able to maintain .05 exactly, all times of the day, forever. All of your test results are all within the range.

Before dabbling in SPS consider how old the system is as a whole. How well can it process food/waste? If the tank has gone through all the algae stages, is well matured, and can thoroughly process input of food and fish waste, start with some simple/cheap SPS.

 

[dbjonesjr]

Phosphate is fine at .03, .09, and even .14

You'll never be able to maintain .05 exactly, all times of the day, forever. All of your test results are all within the range.

Before dabbling in SPS consider how old the system is as a whole. How well can it process food/waste? If the tank has gone through all the algae stages, is well matured, and can thoroughly process input of food and fish waste, start with some simple/cheap SPS.

Tank is well matured, been through diatoms, dinoflagellates, and was getting some signs of GHA a few months back. All the coral I have is perfectly happy as well as the nems. I probably add about 200 mL of alk weekly and periodically add calc (making me assume things must be growing). Have good coralline growth etc.! Everything seems pretty solid and I’m thinking it’s time to try SPS. Like I mentioned the two Monti frags I have in my tank are doing perfectly well with good PE and new growth.

I guess I’m chasing phosphate numbers based on reading numerous articles on higher phosphates stunting coral growth.

 

[RobZilla04]

Tank is well matured, been through diatoms, dinoflagellates, and was getting some signs of GHA a few months back. All the coral I have is perfectly happy as well as the nems. I probably add about 200 mL of alk weekly and periodically add calc (making me assume things must be growing). Have good coralline growth etc.! Everything seems pretty solid and I’m thinking it’s time to try SPS. Like I mentioned the two Monti frags I have in my tank are doing perfectly well with good PE and new growth.

I guess I’m chasing phosphate numbers based on reading numerous articles on higher phosphates stunting coral growth.

Don't chase numbers. Those are well within accepted ranges and shouldn't be altered on purpose unless you're experiencing algae or other issues. Take the signs of other corals as an example. If they look healthy, are growing, and have good color everything is just fine.

 

[Dan_P]

Hi all. I’ve been looking to get into some more SPS (than the Chili Pepper Monti and Purple Monti Digitata I currently keep) so as a result I’ve been keeping better track of phosphates. Come to find out (after picking up a Hanna H713 from a fellow reefer with new reagents for $20!) I have been reading my Salifert kit at lower values than actual. I figured I was pretty close to .03 with the Salifert kit. Hanna is reading around .09 to .14. Will explain the variance in a second. Anyways now to my actual problem and a follow up question.
Tank Information - in the middle of moving to an all out 90G build, trying to get problems solved first
Size: 40G
Light: T-247B
Filtration: No sump on this one
Rock: 25 lbs Pukani, 35 lbs BRS
Sand: Maybe 1/2” to 1”
Feeding: 1 cube mysis 5 days/week (and reef chili per instructions about 2 days/week)
Alk: 9-10 dKH
Calc: 450 ppm
Mag: 1500-1600 ppm
Nitrate: 0 ppm (API/Salifert, have considered dosing)
Phosphate: as described
I started running Phosguard after learning my phosphate was higher than I would like at .14 ppm. Initially it didn’t do much (older stuff had been in the reactor without water for about a month or two) so refilled it with new media. Got my phosphates down to .09 overnight (this was tested yesterday morning). When checked last night my results were .10. Stopped running the reactor (have read about phosphates being leached back in from the media after it is saturated). Checked this morning and got .12 on the Hanna with the Hanna reagents. Now on to a couple of my actual questions.
As I didn’t feed between last night and this morning is it possible that my rocks are leaching phosphate back in? Or is it likely just food that is continuously being broken down?
As a test out of curiosity I used Salifert phosphate reagents in the Hanna checker. I got .14 vs .12. Is it possible to use up my Salifert reagents in the Hanna (to get my $20 out of it). I figure at this range it probably wouldn’t hurt to use it till I can finally get them down to my goal of around .05.

I found the Salifert absorbance in the Hanna Checker was a bit lower, with limited experiments maybe 10% lower. I also found that if I was not very careful to tightly pack the little red measuring spoon with the solid reagent, my test results were low. So, yes, use up the Salifert reagents.

As for variations, the size of variation you are observing is most likely in the method. The Checker device itself gives a slightly different number for the same solution upon repeated measurements. That is normal. The exact amounts of test chemicals used per test varies, no matter how good you are, and that adds a little more variation. Unless you determine what the variation in the method is, you cannot make a strong case that 0.09 is different from 0.10 ppm.