Phosphate in food

[MitchM]

Seeing as how P04 levels in our tanks seems to keep creeping up, I tried a test yesterday to see how much is in the food that we are feeding the inhabitants in our tanks.

I took a single 7 1/2 x 8" , 2.8 gram piece of nori and placed it in 1 liter of RO/DI for 24 hours at room temperature and tested the water before and after.

Before P04 was 0.0 ppm.
After P04 was 1.0 ppm.

The only nutrient export systems that I am using are protein skimming and water changes, which are not enough as I am seeing more cyano growth and small patches of hair algae appearing.
I would like to get some macro algaes growing, but my sump and main tank have large algae eating fish in them, most of which are being transferred to a new system soon.
I'm looking forward to seeing if planting some macros will work to take up the P04 fast enough to compensate.
I measured my tank water and it showed 0.5 ppm P04 before the water changes that I am now doing.
I'm going to do the same test with some frozen mysis, rinsed and unrinsed next.

edit:
18 grams (about a tablespoon) of Piscine mysis, unrinsed, showed about 2.0 ppm in the same test.

edit:
18 grams of frozen mysis, thawed then rinsed briefly in R/O brought the weight down to 14 grams. P04 was a little over 1.0 ppm.

Mitch

[Delphinus]

Very ... illuminating. 1.0ppm from one sheet of nori is impressive.

[Canadian Man]

Stop feeding nori! As much.

Yes I'm serious.
I have stopped feeding my whole sheet of nori every day and have cut back to 1/2 sheet every 4 to 5 days.

This has been a big change for my huge algae eating population, but, they are all still very fat and have been for the 2 months I have been doing this.

Just a thought.

[MitchM]

What are they eating instead, Jonathan?

Mitch

[AJ_77]

Good question - another question I have is, would it be safe to multiply liters and get the likely effects a sheet of nori (unconsumed) would have on 100 gallons of water?

Also, could you do the same test in some tank water, Mitch? I know, I know...

[MitchM]

Originally Posted by AJ_77

Good question - another question I have is, would it be safe to multiply liters and get the likely effects a sheet of nori (unconsumed) would have on 100 gallons of water?

Also, could you do the same test in some tank water, Mitch? I know, I know...

I'm sure someone could come up with some sort of math equation for P04 in ..P04 out.
Do you want new tank water or old, Alan?
I've only commandeered one measuring container from the kitchen for now, I'd be pushing it for another.. , and right now it's got mysis in it...

Mitch

[AJ_77]

It would be simple multiplication, if the relationship is the same per volume of water. It may behave differently when immersed in a bath-tub full of RO, for instance (or not)...

And I guess new tank water, thanks.

If you need containers, I've been squirrelling away a couple... if my wife sees me use anything for the tank, she now sets it aside as "not fit for human use" - and it becomes fishroom property.

[EmilyB]

I don't think it's a good idea to leave unconsumed nori in a tank for more than a couple hours, and never have.

I wouldn't ever cut back on what my fish consume however.

Do a water change....

[AJ_77]

Originally Posted by EmilyB

I don't think it's a good idea to leave unconsumed nori in a tank for more than a couple hours, and never have.

So how much do you put in at a time, and how long then does it take for your horde to finish it off?

[EmilyB]

LOL Alan, it takes them about a half hour to consume a 2 x 4.

1-2 flake feedings, one frozen feeding, and sometimes a pellet feeding.