Lifetime Charter Member
Lifetime Member
Jan 24, 2005
Reading through some of the posts, I noticed a particular reference that mentioned phosphates were important for red plants. Is this correct? Would chelated iron have any more importance for red plants than for green plants? I'm one of those old geezers who is hesitant to add phosphates (my heart misses a beat when someone mentions it). I'm still getting over nuking my tank with nitrates- but boy, does it work!


Gill Man

Prolific Poster
Feb 10, 2005
San Francisco
Re: Phosphates

I do not see a reason why phosphates would affect the color of red plants. The red, orange and yellow pigments in plants are from a family of pigments called carotenoids. The chemcial structure of carotenoids is a carbon lycopene chain with some side and end groups. The coloration comes from the amount of carbon=carbon double bonds in the chain and has nothing to do with phosphate.

Phosphate is collected and stored by plants for other biological uses. They don't need a whole lot. 1-2 ppm in a highly lit tank with CO2 and nitrates is not a big deal. Through testing, I have found that the plants in my tanks, in their current condition and mass, remove 1 ppm phosphate per day. This could change if I do some heavy pruning, or change the lighting duration, etc.