Phosphate Problem. help!

I have beat every single problem I have come up against in the reef hobby in the past 23 years...but this problem is really not going away...and I am getting beat so far! The game is not over but man o is really bugging me!

300 gallons of water in my reef after displacement
High feeding level for large livestock including 3 sheets of nori a day, pellets,
phosphate at .28 4 days ago and at .53 today...arggghhhhhhhhhhh

Solutions so far not working:

1. large media reactor running GFO> far..useless!!!!!!!!!!!!!! and expensive!

2. algae scrubber..yes .. works but too little to make any significant change.
3. vodka dosing in 7th week with MB7 Microbacter - so far no change.
4. 10 percent water change weekly except past 2 weeks. but doing one
tonite. (ran out of salt!)

5. tried bio beads..useless but...only 4 weeks or so online and did not really
get a fair test I must admit.

6. phos bus chemical added...40 bux a bottle waste of money!!!!!!!!
insignificant result except temporary change.


I need a turbo fired method of reducing phosphate....
I do not want to reduce feeding or fish....there must be faster turbo
fired method of getting rid of phosphate???????? I need much stronger
method then all the above.....

I am thinking of trying the bio beads again and giving them longer to work
this time......but again..I am wondering if another waste of money????
I want to get into SPS and I cannot with this level of phosphate is my fear!

comments, suggestions, opinions all welcome good or bad.

Fire away!


Thanks kindly for your help people.


"My God Reefs are Gorgeous!"

Current Tank Info: 280 gallon reef


New member
are you still running the algae scrubber? I've had great success with mine...granted my tank is much smaller than yours.
not the phosphate test kit.

not the phosphate test kit.

Thanks but nope..its definitely not the test kit.
I use a digital tester that is bang on...for sure.
Yes I am still using the scrubber and it is doing it;'s job but it is just not making
significant difference likely due to the amount being fed into the water.
I could reduce the feeding and reduce the fun and reduce the livestock but damn it
there must be another way of just removing the phosphate.
I am thinking of increasing water change to 15percent a week from 10percent but
man o man....necessary????


Reefers Digest

New member
Try adding a refugium to the mix. Something capable of holding a large amount of macroalgae. I'm looking around for an old paper I read on the most efficient species for nutrient export... but I can't seem to find it, if I do, I'll edit my post. In the meantime, I'd stick with chaeto, it's a fast grower, and with enough of it, should put a serious dent in your phosphate readings.


i have 50 gallon refugium with enough cheato to fill a 5 gallon pail.
I prune it monthly and throw out about 2 -3 gallons



Premium Member
Seaklear - Lanthanum Chloride. Your large tank / crazy feeding might make it a good candidate. There are some old threads on here that describe in detail how to dose it and how not to! Good luck!
SLC scares me...sounds like it will be amazing but that not enough research yet to
show it is safe and there are claims of damaging or marking glass possible etc....
I am using starfire and I sure dont want to damage anything it sounds like the perfect thing for me I am afraid to try that....should I be?????



Premium Member
Lanthanum chloride might have some risks, but I can't think of anything else that might work and not cost a lot of money. More GFO would do the trick, but it'd be a lot of medium, changed every day or so, at least for a while.


New member
go spend $18 at petco and buy a jug or 2 of Kent Phosphate sponge, each jar treats 120 gallons, put it in a filter sock and rinse it good then place the sock under your return flow in your sump, leave it overnight then take it out, with the amount of water you have you might need 2 or 3 jars but i used one on my 125 and my PO4 went from 1.5 to . 5 over night, now i have my Pgosban 150 running and my PO4 is staying under .5 and it's only been 2 days of running it. i have rock in my tank that is over 5 years old and some of my sand is also. That's where i think I get my PO4 from it all leaching out, hopefully it will eventually stop. I just cleaned my ATS for the first time in 2 weeks,so see how that works. Kent Phosphate Sponge...hopefully you can find it cheaper, but that's what it costs at the store near me..But it really works and in less than 24 hours
As Jon has stated the GFO will work, but you would have to change it out about every three days or so until your phosphate becomes undetectable. FWIW, GFO will most likely become saturated within 24 hrs at the phosphate level you have. You will also be pulling phosphate out of your rock and sand that has become attached. This takes longer to reduce. ;)

You can economically regenerate GFO.
Last edited:
What brand of GFO are you running? I know they're basically all the same but I had the same issue, with it being stuck at .5 for a week; ran GFO and it dropped to .25 but no further

My local, saltwater, LFS recommended using Rowaphos and it dropped to 0 overnight. I still run it at a fairly slow flow and they've never come back up. I had the same issue: older tank and I tend to over feed as well (keeps the aggression down)

Good luck...and I (as in myself, personally) would definitely go with the larger water changes. Very hard to do with a tank of your size, I know


New member
I read in one of the threads that API test kits sometimes won't read less than .25 PO4 even if it's less


Ultralife has a product for 20 bux of which 1/2 the bottle will bring me
to .03 they advise! mmmmmmmmmmmmmmm......

I use phosphate digital tester and it is bang on.
There are no test kits for phosphate that can give the accuracy of
my digital tester from is excellent! I highly recommend it.
Without it...I may not know I had a problem lolol



New member
Just a thought, test you make-up water. I have seen PO4 levels as high as 0.68 ppm. Therfore, you may need to treat you make-up water prior to mixing in you salt. This would also explaing the continious residule of PO4 with all the methods your trying. Water changes may be your source. Additionally if you are feeding frozen food if you thaw and rinse them with a plastic coffee filter you can flush out any PO4 that was used as a preservative.
Last edited:


ReefKeeping Mag staff
Premium Member
Kent phospahte sponge is aluninum based ,I bielieve, with potential for irritating corals. The ultra life product is likely lanthanum chloride. SeaKlear is a lot cheaper. Lanthanum chloride is cetainly powerful and fast. I've used the SeaKlear and still do when I need to cure rock that is leaching PO4.. It needs to be drip dosed and well filtered if you are putting it in a tank. If the tank water clouds with precipitant it can be harmful to the animals in the tank.
SeaKleer in tank

SeaKleer in tank

Have you used SeaKleer in a display tank at all ever?

How much did you use and on what size tank with what phos level and result?

Thanks much.... Did I hear on here that it can damage glass?

Is the stuff safe if used as directed?