Ineffective at measuring aquarium phosphate levels. Not even close to a granular enough measurement.

Every one should tests phosphate levels of water whether it is for livestock, drinking or showering. You should also test often as water changes drastically due to neighbors overuse of pesticides. Please stop P ing in our aquifers.This lets you know whether your reverse osmosis or other flirtation system is working. If you use strips and now know you have issues it does not matter which color it turned, u need to correct problem and test again. Once you have under control and are below the threshold cut off of these strips (meaning no color change) them send to lab to see if your are at zero. I don't need anymore phosphorus as phosphate used in EVERY single packaged food from crackers to McDonald's so even though I don't eat meat I have plenty of phosphorus intake as even in prescription medication. We are being poisoned with the level of phophorus and many doctors will tell you maybe you have kidney disease but it will just be the ridiculous amount if phophorus your are intaking.

Simple, gives your results in 3 minutes. Using for 15,000 gallon pool. Only comes with 50 strips, but once your phosphate is under control, it's not something you need to test every week. Just primarily in spring and fall when debris falls into your pool.

These strips are not accurate with experience. It could be that I use bromine as a sanitizer in my pool, so they may work as intended for other applications. Also, the strips came packaged with the test pad end at the top of the container, so you end up touching the pad and possibly contaminating it!

I was having problems with yellow (mustard) algae in my pool.I took a water sample to local pool supply store for a free test. Their equipment showed the water had over 4000ppb (parts per billion) of phosphates where normal range is below 100ppb. They said phosphates in the water feed algae.Plus, currently having a drought where I live, draining and refilling pool wasn't an option as it would violate a city ordinance.So, they sold me a bottle of a concentrated phosphate remover.For size of my pool (just under 10,000 gallon), I had to use 1/4 of the bottle at a time then clean the DE filter between doses.Before I was done, I purchased a second bottle of it from Amazon at about half the price of the local pool store.Meanwhile, because of gasoline prices in my area in the $9+ per gallon, and distance to the pool store, I ordered these test strips to eliminate need go to the pool store weekly for water testing as I was doing the phosphate removal.Usage instructions for the strips said dip for 1 second then wait 3 minutes to read. I tend to be a bit impatient so that 3 minute wait time got frustrating. Though, 3minutes was less than time to drive to the pool supply store.This 3 minute wait time for a reading is why i gave the strips 4 rather than 5 starsOverall, the strips worked.Once a strip said the phosphates were around 50ppb, I took a final water sample to the pool supply store. Their equipment said the phosphates were 52ppb (normal range).I then used Yellow Gone (same chemical as Yellow Out) and liquid chlorine, to kill whatever algae was left in the pool and brushed it before and after that.If my the CYA (aka conditioner) in my pool wasn't very high, I would have used a bag of shock (which would have added more CYA) rather than liquid chlorine. But, only way to remove CYA is to drain the pool which is currently not an option.