Sanity check please

[prh129]

I have a 24' AG (13500 gal) pool which was just filled last week (trucked in). I picked up an HTH 5-way test kit while I'm waiting for the PS234 kit to come in. Here are the numbers from that kit:

pH - 7.0
TCL - 2.5
ALK - 30 ppm
Hardness - 1000+ (note: the kit says the solution is supposed to turn from red to blue. The sample was originally yellow after adding the 5 drops of blue hardness indicator then slowly turned green then eventually greenish-blue. I tested this on my tap water and the sample was blue right off the bat.) I figure since this is a liner pool I can check this against the PS234 kit when I get it.
CYA - less than 30

I only added about 1 lb of CYA 3 days ago so I know I need to wait a little longer before getting an accurate reading.

I've been adding about a quart of bleach every day although none was added yesterday.

It looks like I should bring up the pH some so I'm thinking I should add about 1 lb of Borax. I was going to retest later this afternoon and check the alkalinity again and if it's still low, I will add about 4 lb of baking soda and retest later tonight and keep adding to get it to at least 80 ppm.

Since this kit doesn't test FC (and it's too cold here to swim anytime soon) I will just keep the TC around 3 for now until I get the PS234 kit.

Does this sound right?

Thanks

Peter

[mwsmith2]

Your approach is sound. Odd hardness results though...dumb question, but are you using the correct reagents?

Michael

[prh129]

I checked and double-checked - I even did the test twice getting the same results both times. The reagents have color coded lids and the hardness test described in the blue section of the directions uses the reagents with the blue color lids - the first one (Hardness INdicator) is a blue liquid - I put in 5 drops of that to start and swirl then add the other reagent (Hardness Titrant)which is clear one drop at a time. I was swirling the sample after every drop of the Hardness Titrant but the second time I would add 5 drops at a time and then swirl.

When I first put in the blue reagent, as it mixes in I see the blue strands turn red but it quickly disappears and the sample looks yellow. When I did this test using my tap water as a sample, the whole thing turned blue when I added the 5 drops of the first reagent.

I wonder if there is another chemical in the pool water that is reacting with the reagents and messing up the test.

At this point, I'm not too concerned about it so I will see what I get when the PS234 kit shows up.

Thanks for the help.

Peter

[prh129]

I just realized I recently got some Sofchek hardness test strips because I just got my water softener serviced and the meter no longer works so I wanted to figure out how many days I should go before regenerating.

I ran the test strip on my softened water and the pool sample and both came up near 0 gpg (0-25 ppm) in color. I then ran a strip on the incoming water from the well and got a 7 gpg (120 ppm) reading - I know from past water tests that the raw well water was about 8 gpg so this seems about right.

It looks like something else in the pool water is messing with the HTH hardness test.

Peter

[waterbear]

I have had similar problems with the aquachem hardness test (pretty much the same results of it working in tap water but not in pool water). I find it works better if I put in 10 drops of the hardness indicator. It then gives me results very similar to the Taylor test for CH. The better hardness tests such as Ben's and Taylors use 3 reagents. The first one is to help remove the interference from the magnesium in the water by precipitating it out as magnesium hydroxide. The HTH and Aquachem don't. Perhaps this is the problem.

[vanhout]

I had the same problem just yesterday. HTH kit wasn't working, but Ben's was. I'm at 12 FC right now, I figured it was related to that