Best Macro for Phosphate
 

Was curious, is there any data or experience out there with macros and phosphate removal? In other words, which macro sucks up the most in relation to nitrate?

I don't know if there is any significant difference in uptake of inorganic phosphate between species of algae, but I grow a couple of species of green ulva on a scrubber screen & it removes PO4 very effectively.

Macro absorb nutrients in the same ratio. It is called the Redfield Ratio at 106/16/1 of carbon/nitrogen/phosphate

That's not actually correct. The ratio does variy from place to place somewhat, & in any case the redfield ratio is not a regulator for how much of each nitrient any particular organism takes up.

The atomic ratio C:N:P in phytoplankton is 106C:16N:1P, while bethnic plants (mean of 92 species) on average have a somewhat higher ratio of 550C:30N:1P. These ratios indicate that many seaweeds are more prone to N limitation than phytoplankton.
The ratio of two nutrients that is required for maximal growth of a seaweed is called the optimum ratio. As stated above, the average N:P ratio for seaweeds is 30N:1P with a range from 10:1 to 80:1
http://sailing-sea-farm.com/onewebme...v%C3%A6kst.pdf


Analysis of the annually-averaged 2001–2010 monthly nutrient data from 13 stations in the Venice Lagoon (Italy) shows that the concentrations of dissolved nitrogen (N) species, measured as total dissolved N (TDN), have increased over time while that of phosphorus (P) species, measured as total dissolved P (TDP) have decreased. During the study period, the TDN/TDP ratio in the lagoon rose from about 46:1 to 100:1 (by atoms), a level at which the growth of benthic macroalgae is favored over that of sea grasses.
http://levin.ucsd.edu/people/photos/...V180_33-41.pdf

Twin,
Thanks for the details. Yes, there are more exceptions than rules. I thought it best to keep it simple, because the OP asked about phosphate uptake.

I have changed the ratio in plants by heavy iron dosing, not only with a dramatic change in color but with a feature called “nutrient storage”. When Gracilaria Hayi took up excess iron, instead of thin calcified blades, the blades increased in thickness and felt spongy.

The 30:1 ratio of N:P is what was analyzed on Red Ogo, when I grew it.

There is no doubt, that seaweed will absorb what is in the water.

IMO, the best to use is what works for you. Where your growing and what your doing with it. I grow mine in a refugium and focus on the plants my Tangs like to eat the most.

Thanks all! Guess there is no getting around water changes and GFO!

I add ammonia and harvest macro. No GFO and no water change.

Not at all. If your method for growing algae for filtration is designed properly you shouldn't need gfo or any thing else to controll PO4.
I barely get a reading on a salifert tester, and occasionally dose potassium phosphate to ensure there is enough.