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How accurate are the phosphate test kits? The ones I have has the tube that you fill with water then drop the tablet in & compare the blueness once the tablet disolves.
Some may remember that I have continual phosphate problems which leads to algae regardless of my chlorine levels. I check the phosphate level of my tap water yesterday & came up with the darkest blue on the comparator which signifies 2500. Just wondering if that were accurate or not!
What is the make of the phosphate test kit? I have acutually used a phosphate kit for aquarium use (powder reagent) to test my pool and the results were identical to the results from the pool store. They all basically use the same reagent that turns blue if phospates are present. The difference would be in the comparator used. Printed ones on cards are usually not quite as accurate as either plastic or liquid tube comparators. Then again the phospate test for a pool does not need that much accuracy. You just need to get to 0 ppb (or, at least, under 200 ppb) phospate if you are going to treat for it. It is entirely possible that your tap water has high phospate levels so testing tap water would not tell you if the kit was accurate or not.
Phospate kits measure in ppb (parts per billion) not ppm, usually.
My question is, why are you worried about phosphates? If you do not have an algae bloom that you cannot kill it really isn't important. If you do have a resistant algae bloom then removing the phosphates from the water will help only if phosphates are the 'limiting factor' in the algae growth. If there are also high levels of nitrates in the water removing phosphates will have little or any effect at controlling the algae since nitrates are also a favorite algae food! (the amount of carbon dioxide in the water also has an effect on algae growth...this is influenced by a combination of 2 factors: your pH and kH--carbonate hardness or total alkalinity)
If your fill water has high phosphate levels as your test indicated and there are no nitrates in the water also then treating for phosphate would be effective. You might want to do a check on your fill water for nitrate also.
The test kit is made by Natural Chemistry.
I have been round & round with alge blooms for the last 2 years. Water always test fine as far as my clorine levels & stabilizer levels. I even tried keeping the cl higher than needed according to the charts available here & still ended up with green water after a month or so.
Nitrates have NOT been found in my pool water. Last summer, I treated for phosphates ( major pain in the butt! I only did it as a last resort) & went the next two months with clear water. I don't think I got the levels down as far as they are supposed to be but it was far enough to help control the algae.
Too bad the info from last year isn't available, I had lots of posts regarding the problem & also got quite a bit of feedback from the "pool god" Ben!
Well, It seems you have found that your 'limiting factor' IS phosphates.
I've looked over the NaturalChemisty test kit myself and it seemed OK for the price. Chemisty behind it is sound! Basically the same as most of the aquarium phosphate test kits. There are liquid kits available but they are pricey! I wouldn't worry about the accuracy. You basically want to get as close to 0 ppb phosphates as you can! (no blue color) Bottom line seems to be phosphates in your fill water so their products (or other lanthenum chloride based products) should work for you! You will probably need to to the full treament (yes, it IS a major pain in the butt, but it actally works!) to get as close to 0 ppb as possible and then add a maintenance dose every week or two, espececially after adding water to your pool. Good luck!
Thanks WaterBear...I plan to pull a tapwater sample tomorrow & get the phosphates tested so I can compare their #'s to mine.
I had the phosphates checked on my tap water today. He came up with about 450ppb on 3 different tests. Only problem is, he was using strips from 3 different suppliers. I tried to find someone that could test it without using strips but drew a blank. Those here in town that could test it used strips.