If Phos. in a planted tank are required what is your opinion on Phos. in a saltwater reef tank?
I am under the impression salt water reef tanks want 0% phos. (unless you are being a SW algea farmer)

Predominantly because most salt water life has evolved to an extremely high dillution rate. It would be challenging to utilize enough phosphate in a closed system. While some species will tolerate it, it's generally not good in the long run and certainly detrimental if not lethal to delicate species. Unfortunately that mindset spilled over into the freshwater hobby, and the dynamics are completely different in FW planted systems. HTH. Prof M

So Phos. in SW is a bad thing then.

Are you growing turf grasses or macro algaes ? Most any photosynthesis will require some phosphate. Just considerably less than we are use to seeing in FW planted tanks. Zero phosphate on the other hand won't work ither, but it's pretty hard to acheive Zero in a closed system so it's a safe margine for most reef tanks. If on the other hand you are cultivating macro algaes, or turf grasses you're going to need more phosphates. Saltwater eco-systems are alot more specific when it comes to nutrient potential. This was a pitfall of early minireef sytems. Many people found out the hard way. HTH. Prof M

I am growing corals and don't want turf grass or macro algea,just some sps & lps.
I just wanted to make sure i was on the same page due to having my eyes opened recently with the Phos. in a planted tank and the importance of it in a planted tank.
Thank you.

For Corals you'll want to keep PO4 below .3 ppm The lower the better whether it's toxic or not is subjective. More importantly it contributes to brown algae and chokes out the coral. Best media I've found so far is Rowa Phos in a fluidized column. I don't do this schtick any more ! P.S. Never ever use this in a planted tank unless you sincerely want to know what will happen. HTH. Prof M

Thank you!

Slightly measurable PO4.
Some macro's in the refuge will help.

Absent PO4 will cause some corals to grow slower, the algae inside them needs some PO4 sources, generally from the food sources the coral animals catch, so in general, happy animals, happy micro algae in the coral= happy colors/overall coral health.

I'd not suggest dosing PO4 to anything other than a well run macro algae tank etc and then .2ppm or so, or less even.

It's nothing like the FW planted systems. Many algae have adapted to limiting PO4 levels, unlike FW systems.

Regards,
Tom Barr