Any credible way to test phosphates?

[JLAudio]

I cant figure out what is causing green algae to form on back of tank, front glass and hair algae on a few rocks

I use all rodi water
Weekly 10% water changes
0 nitrates
Skimmer rated for 4 times the tank size
Phosphates 0 but Aquarium pharm kit, so dont think that means much
I feed every otherday.
Photo period (12 hrs. PC and 8 hrs. MH)
Live stock in 54 gallon only 5 small fish.

Just cant figure it out, I assume my phos kit is wrong and im looking for a credible one.

I also just changed my light from a 20k XM to a 14k phoenix and noticed a lot of algae increase, but it was there previous to change, just not as dramatic

 

[ssmtcarlo]

To get an accurate result you need a hanna meter. if anything shows on a test kit you phos is prob to high

 

[boozeman]

you can try a low range phosphate test kit like the DDmerk

 

[figgy]

Hanna Meter. Can't believe I went so long without it. Expensive but you get what you pay for.

 

[Tonyscoots84]

one word as already said HANNA........

 

[basiab]

The problem is that the algae takes it all up so when you measure it is zero. You either have to eliminate it to begin with or get something that will suck it up before the algea does. And that is the idea of a fuge. You put chaeto or whatever in the fuge, it uses up the phosphates and your display stays clean.

 

[JLAudio]

Currently I am running a phosphate reactor, with phosban in it, but I do not have a fuge.,

I am going to look into a hanna meter, so at least I will know the answer because my test read zero