Accurate test results

[Pamsel]

I'm hoping someone can help me with this. Two days ago I took a water sample in to the one pool store in the area who is supposed to do accurate water testing. I wanted to have it tested for metals, since I can't test that.
The test results were so vastly different than my numbers with my Wal-Mart drop kit, that I am really unsure which is accurate.

My TA is still high ~ tests in the 320-340 range at home; the pool store test showed 210.

My CYA tested 25 last week, theirs showed 0.

When I test for hardness, the kit says that when I add the hardness indicator, the water should turn red if there is any hardness. My water turns a very slight yellow-tinted clear. The pool store test says my hardness is 367.

Their test showed no iron and .2 copper, even though I know that the water I top off with is high in iron and I had overdosed it on copper algaecide about 3 weeks ago. I have put a sequestering agent in 3 times since then. Would this account for the test showing no metals?

Also, when I use the dilution method to test my CL, I don't seem to get accurate results either. I am using reverse osmosis water, rather than distilled to dilute with. Would this make a difference? When I test without dilution, my color is deep yellow - almost yellow-orange. But when I dilute and multiply, it comes out to 6-7 ppm, which I know is not correct. What am I doing wrong?

Thanks for any help!

[CarlD]

Use steam distilled water--every big drug chain and most supermarkets have it. Reverse Osmosis is a technique for making sea water drinkable, but cannot be used in polluted areas, like bays and harbors, only on the high seas. It's basically a portable de-salinator.

[waterbear]

First, test results are only as good as the people doing the tests
Second, they are only as good as the test kit used.
I cannot comment on either your or the pool stores testing methods but I do know this. The CH on the walmart Aquachem kit does have some problems. The indicator turning yellow has been documented by myself and others in a different thread. Sometimes this test works fine and sometimes it doesn't. I suspect that high chlorine levels are causing the interferance.

The copper and iron results you got mean that the sequsterant you added had worked and made the metals in your water non reactive or that the testing procedure is not correct.

If the pool store is using LaMotte testing (small plastic vials of powdered reagent injected with pool water) then I can explain the low TA readings. The TA test needs to develop for 1.5 minutes and needs to be read before 5 minutes has elapsed. If not it will read low. (It will also read low if the chlorine levels are above about 6 ppm but it doesn't seem to really affect the test until the chlorine gets to about 9-10 ppm) Ditto for the CYA test except it needs to develp for about 2 minutes as does the copper test. The iron test is supposed to develop for 3 minutes before reading. Also the LaMotte test is a total hardness (calcium and magnesium hardness) test and not a calcium hardness test.

If they are using a different test chemistry then I really don't know except that some pool store water testers really don't do a very good job with their testing.

[waterbear]

Use steam distilled water--every big drug chain and most supermarkets have it. Reverse Osmosis is a technique for making sea water drinkable, but cannot be used in polluted areas, like bays and harbors, only on the high seas. It's basically a portable de-salinator. Reverse osmosis removes almost all dissovled solids from the water. If it is followed by carbon filtration it then removes soluable organics and chlorine from the water.

[Pamsel]

I don't know what kind of test system the pool store used. They are an AquaBan store. They used a test strip that they dipped in the water, then put on a little tray that slid into a machine that came up with the readings. There were no small plastic vials with powdered reagents.

Their test also said that I have no more algae, which I am not sure is accurate either. All I know is that the appearance of my water has remained basicly unchanged for two weeks, in spite of everything I have done to correct it. It has been a little less cloudy a day or two but when I brush the pool it stirs everything up off the bottom and sides and the water becomes totally dark and cloudy again. It doesn't seem to get filtered out or cleared up by exposing it to more CL.

[waterbear]

The are using test strips with a colorimeter. This is similar (or possibly is) the Alex system by Bioguard.....Run, don't walk, to a different pool store for your tests....Based on this info I would trust your Aquachem results over theirs!

[Pamsel]

Actually, I think I posted that wrong. I believe they are a BioGuard store - not AquaBan. They actually call themselves "your accurate water testing center"! The other main pool store in my area only uses test strips - same as I used to use at home. All the other stores in my area are either branches of these two, or very small stores. I'm going to have to search the yellow pages and call around. I may not have a place to get my water tested accurately.

[CarlD]

Actually, I think I posted that wrong. I believe they are a BioGuard store - not AquaBan. They actually call themselves "your accurate water testing center"! The other main pool store in my area only uses test strips - same as I used to use at home. All the other stores in my area are either branches of these two, or very small stores. I'm going to have to search the yellow pages and call around. I may not have a place to get my water tested accurately.

Yeah, they aren't going to say "Your in-accurate water testing center" are they?;) Which, of course, unfortunately, is what they really are.

The best solution is a good test kit. There are 3 that I think are good. First, Ben's PS-234--but do a search on that here. That's simply the best organized, easiest to use, and ultimately the most economical as it comes with its own refills. Then there's the Taylor 2006 (available on-line from Taylor chemicals). Finally there's the Chlorine FAS-DPD Service Kit from Leslie's on-line site, which is also a Taylor-made kit. All 3 use the FAS-DPD method for testing chlorine, which is the best for home-owners. Also Taylor will sell just a FAS-DPD test kit, and Leslie's used to have their own version of it-- same test, packed differently.

If used correctly, all three should give nearly identical results as they basically use the same tests

The cheapie alternative, if you can get it, is the WalMart HTH 5-way drop test kit. In some parts of the country you can get it easily, where I am, it's no longer sold. But for $12-$15 it's a heckuva bargain and it DOES work well.

You can buy separate copper and iron test kits because they usually aren't in the regular kits. But the two kits together cost more than Leslie's FAS-DPD kit!

[Pamsel]

Thanks Carl. I have just ordered Ben's kit, but don't know how long I'll have to wait until I get it. Seems there's been some problems getting them shipped out promptly. Until then, I do have the Wal-Mart kit and will do the best I can with it.