The most accurate are probably the digital/electronic's if you have the bucks. I just changed out the media, kind of a PITA, good thing my girlfriend only see's about half the water I spill :mrgreen:

I'd go with "precise" over "accurate". At least IME. :)

I once read a thread on the Salifert forum where Habib said level as opposed to rounded did not matter to the end readings. However I have not tried the two at once to see.

I just bought the Hanna LR meter because I was skeptical about the readings from the color based tests. My Merck and Salifert test were reading in the range of 0.015-0.03 but I was still having problems with hair algae and some cyano. My RO/DI water reads 0 with the Hanna meter. However, water from my tank and the phosban reactors (250 ml Rowaphos and 300 ml PhosGuard) ranges from 0.03-0.05. I'm not sure what to make of all this.

That hair algae and cyano are a pain! I have a lot smaller system, but my cyano seems to have disappeared after months of fighting, but my hair algae has increased. There are some good articles on reefcentral about using a phosban which is what originally sold me on it, but I have yet to see great results. That being said, without me knowing my media may have been exhausted, which is....my fault :biggrin:

A lot of Po4 is being stored in live rock and sand, that is why you still have hair algae.
keep up agressive Po4 filtering :wink:

I agree. When I first got my phosban reactor, I did have a rapid improvement with my hair algae. It eventually has come back. I have been more aggresive with changing my ROWAphos (now every 1-2 weeks) and have much less cyano. I have not seen much change in my hair algae but it may take a additional weeks to see a change.

1-2 weeks! :eek: Just curious, have you actually tested your reactor effluent with the photometer and you noticed a difference in the levels?

I'm not testing fanatically anymore.. but I noticed my reactor effluent was 0.0 for about 2 days then after that it started to climb. So now I'm wondering now if it wasn't precision error (ie. the "to within 0.04" thing) after all, although I still think 2 days is awfully fast for phosban to exhaust itself. :neutral:

My Reef consistently reads 0.01. My Trigger tank reads anywhere from 0.075 to 0.25, depending on the age of the RowaPhos. The difference between the two tanks in relation to this? The Reef has hair algae and multiple types of macros and the Trigger tank’s algae is minimal. I think the two tanks may have similar phosphate levels,....just that the phosphates in the reef are primarily in the alga, and the phosphates in the Trigger tank are in the water. I stopped using RowaPhos on the Reef about 2 months ago because of the consistent 0.01 readings. So far, so good. The Trigger tank RowaPhos gets changed out every 4 to 8 weeks. It’s a challenge getting that one below 0.075.

Cheers,