high phosphate in new tank before even cycling

dave48 · Jan 30, 2023

just setting up a new 5 ft tank for soft coral/lps and prior to cycling I tested all the parameters so I had a baseline to work from.
All fine except high phosphate at 0.6
I used dry rock, dry substrate etc so very surprised at that level. I have tested my RO filtered water and it shows zero as it should.
As no biological matter had been introduced I can only surmise it has leached out of the rocks or substrate.
Im hoping Its a one off and I can get rid of the Po4 with some thing like rowa phos? Is that the best option?

Spare time · Jan 30, 2023

Was the rock previously used?

dave48 · Jan 30, 2023

Spare time said:
Was the rock previously used?

Some of the rock was from a previous tank but it was thoroughly washed, bleached, washed again and air dried.
The rest was bought new and unused. The substrate is TMC ecosand which did cloud the water and took a long time to clear with the help of some seachem clarity.

Spare time · Jan 30, 2023

dave48 said:
Some of the rock was from a previous tank but it was thoroughly washed, bleached, washed again and air dried.
The rest was bought new and unused. The substrate is TMC ecosand which did cloud the water and took a long time to clear with the help of some seachem clarity.

It could be releasing phosphate bound the the rock from before. I'd just throw a bit of gfo in a bag into the filter or sump (sock) and let that take it down.

Randy Holmes-Farley · Jan 30, 2023

Some new dead rock can also have a lot of phosphate on it.

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dave48 · Jan 30, 2023

Do I need to go to the expense of a reactor for the GFO or will a bag in the sump work OK.
I can see putting it in the filter sock would subject it to a decent flow so that sounds good - thanks spare time

Spare time · Jan 30, 2023

dave48 said:
Do I need to go to the expense of a reactor for the GFO or will a bag in the sump work OK.
I can see putting it in the filter sock would subject it to a decent flow so that sounds good - thanks spare time

Eh I think its fine in a very fine mesh bag for this purpose. That is what I do if my phosphates creep up for whatever reason or I overdose phosphate.

Poseidon03 · Jan 30, 2023

Spare time said:
Eh I think its fine in a very fine mesh bag for this purpose. That is what I do if my phosphates creep up for whatever reason or I overdose phosphate.

Yeah, I agree with the fine mesh bag. You want something that will continually take it out and you don't really need to hit it too hard since you are starting your cycle. I'd also keep your lights off.