Strange test results

[meeko350]

I live in Louisiana and have a 30ft round above ground pool with either 52" or 54" walls. I usually keep the water clear during the winter because it makes spring start up so much easier. This winter I let it go green and have had a terrible time cleaning it since I couldn't see the bottom. I normally use regular shock at start up when my CYA is low and then switch to bleach. This year I used Super Shock It 73% Cal-Hypo. I used it once a few years ago with no problems. I used it a couple of weeks ago and my pool went from nasty green to a blue milky white. I've added bleach here and there with no change. I tested my water two days in a row using my Taylor K-2006 kit and got the same results both times. My results are as follows:

pH 7
TC .5
FC 0
TA 40
CH 60
CYA 0? (I filled the tube to the top and could still see the dot)

Why would my calcium be so low since I used Cal-Hypo? And why would my CYA be 0 since it had other chemicals in it?

My pH and TA have always been within the normal range so I've never adjusted either in the past.

Is my CH test wrong since it is still milky white or did I bleach my liner?

 

[duraleigh]

Welcome to the forum. :lol: It seems like you are asking the wrong questions.

1. Your first concern should be chlorine. With no chlorine in the pool, it will never clear....never.

2. With no CYA in the pool, your chlorine is quickly burned off by the sun so you end up again with no chlorine and your pool will not clear.

Your questions are valid but, really, have nothing to do with getting your pool crystal clear. Read "The ABC's of Pool Water Chemistry" up in Pool School.

That will give you some basics and give you the ranges that you need to stay in.

Also find PoolMath (at the top of the page) and use it and the gallonage in your pool to dose CYA up to about 30 ppm and then get enough liquid chlorine to KEEP your pool around 12 ppm or so for the next few days.....15 gallons would not be too much at all....it is never wasted.

Next, read "SLAM" in the "How To" section up in Pool School. The SLAM process is what you will be doing and that's the start of getting your pool clear.

Post up in your sig and tell us the particulars of your pool....pump, type of filter

Also tell us what kit you got the test results with.

 

[meeko350]

As stated above, I used a Taylor K-2006 test kit, which I've been using for a couple of years. I also store it in a cool dark place. I used older reagents yesterday and newer ones today. The guide that came with the kit says to balance the water first, startling with alkalinity, so that's why I was asking these questions. I've never had a problem with pH or alkalinity in the past, so this order of doing things is new to me. I usually just shock once with shock and then use bleach for the rest of the summer. My CYA is usually on the high side, so I was shocked that it didn't even register on the test. I used 10 pounds of 73% calcium hydro and 9 gallons of 6.25% bleach over the course of 3 days, so that's why I was confused. I didn't think everything else should be so low just because it used up all of the chlorine so was looking for an explanation before I add even more calcium and CYA.

I have a Pentair Sand Dollar SD40 and a Dynamo pump. Sand replaced last years & pump replaced this year.

I've read pool school before bit will do so again.

Thanks

 

[duraleigh]

Why would my calcium be so low since I used Cal-Hypo? And why would my CYA be 0 since it had other chemicals in it?

My pH and TA have always been within the normal range so I've never adjusted either in the past.

Is my CH test wrong since it is still milky white or did I bleach my liner?

1. Calcium is low but I have no idea why. Of course, it depends on what it was when you started and how much Cal-hypo you added. Did you use PoolMath intending to raise it or did you not test prior to the dosage?

2. I would raise the pH to 7.4 using 20 mule team borax. Your TA will come up as well and both should be fine.

3. There is no reason to doubt your CH test. If your pool water is milky white, I would suggest you perform the SLAM process. High levels of chlorine (as you use in the SLAM) is what will clear your pool.

 

[Isaac-1]

To address your concerns CYA can be lost over the winter through bacterial conversion, often to Ammonia which takes considerable amount of chlorine to remove, or it can convert all the way through to Nitrogen gas and dissipate. For the CH it depends on how much CH you had to begin with, I am not sure what part of the state you live in, but many parts of Louisiana have fairly low CH if on water wells (mine is currently running around 30 ppm), and of course rain water is CH free, so over flow from heavy rains may have lowered the level in your pool, either way not very important on the low side in a vinyl pool.

As to your current state it is hard to say what exactly is going on as one of the reasons we do not recommend Cal-Hypo for the slam process when clearing a pool is that it can tend to cloud the water, which just confuses things. So get your pH in line, get some CYA in there (use the sock method in front of a return) and get the FC back up to shock level with liquid chlorine / bleach and wait for it to clear up.

Ike