Opening Numbers

[SUNNYDAYS]

I just got my Taylor test kit and will put it into use this week. In the meantime I went to the pool store and had them test the water. I feel comfortable with this pool store because last year 3 of 4 samples I brought to them they told me I didn'y need to adjust the water. So they don't shove chemicals down my throat. These are there numbers

PH 8
Ta 80
Calcium Hardness 170
CYA 105
Chlorine 3.5

They told me not to buy anything now, but to do a partial drain and get the CYA down. Because anything I put in now will be drained and the water chemistry will change with the addition of new water.

What Do you guys think? I was going to double check the CYA with my Taylor kit.




16X32 Grecian Vinyl with spill over spa

[Watermom]

I agree with a partial drain. Draining 50% of the water will get your cya down to around 50 which is much more manageable. Do double check the cya with your test kit and if it still shows high cya, then drain. Have you been using trichlor tabs to chlorinate with? They will really drive the cya level up. If you do a partial drain, just use bleach for your source of chlorine. CYA of 50 is OK, but you don't really want it any higher.

[SUNNYDAYS]

I was going to double check the CYA with my new Taylor test kit before I do any draining.

I know people will give me a hard time with my method of chlorination but I currently use the Frog system. We have had the pool for 5 years and this is the first time that we had a problem with high CYA.

[SUNNYDAYS]

I copnfirmed this morning with my Taylor kit that the CYA was 100. Dumped about 12 inches of water and currently refilling. I hope to see the number drop to at least 70.

[SUNNYDAYS]

UPDATE

I drained 12 inches of water yesterday in my 16x32 pool with a deep end and replaced it with "Fresh" water. My Taylor test kit still says 100 CYa and the pool store says 105 CYA. Is it possible to remove that much water and still have the same CYA?

What is going on?

[chem geek]

If your average pool depth is 4.5 feet (which is usually the case if your shallow end is 3 feet and your deep end is 6 feet), then a CYA at 100 should get reduced to around 80 (even if your deep end is 8 feet, the drop should be similar). 100*3.5/4.5 = 78; 100*4.5/5.5 = 82.

The CYA test is hard to measure at the higher CYA levels as you can tell from the closely spaced lines on the tube at higher CYA. I suspect measurement variation or error more than anything else. Either that or the CYA was actually more than 100 (since 100 is the highest the turbidimetric test measures).

I would just do another drain/refill and you should see a drop.

Richard

[SUNNYDAYS]

Yes that will have to happen again. I too was thinking maybe the CYA was higher than 100. The lady at the pool store said their test goes up to 120 or 130 so I am wondering why their first test said 105 and did not read higher. Only thing it could be error in reading their test.

I will keep you up to date.

[SUNNYDAYS]

Update

Cl 3.0
CC 0
TC 3.0
PH 7.4
CH 180
CYA 60
TA 60


I was able to get the CYA down from 100 to 60 will continues to lower it a little more with vaccuum to waste and refill with fresh water.

What do you think about the numbers I know I need to get the chlorine up.

[rilesworld]

Looks good, but you may want to raise your TA a bit as well. Maybe at least in the 80-100 range.

[chem geek]

Your numbers look fine except, as you noted, the FC should be closer to 6 ppm or certainly an absolute minimum of 4 ppm. This is to prevent green algae. If you are in an environment that frequently gets mustard/yellow algae, then an even higher FC of 9-10 would be required, but only a few pools seem to need that.

Of course, keep working on dilution to get your CYA down even lower so you can run with lower FC levels.

I assume that since you are using bleach or chlorinating liquid that your pH is relatively stable even with your low TA (which is fine unless you have a pH issue). I also assume that with your vinyl pool you have no tile line with grout or any plaster/gunite/grout exposed to the pool water whatsoever (just making sure).

If you are using bleach or chlorinating liquid for chlorine, then please make sure you add it VERY slowly over a return at the deep end so that it can dilute in the return stream and flow towards the floor drain and the skimmer on the opposite side (if that's how it's set up). There is a very experienced installer of pools on another site who is sure that every single vinyl replacement has been with someone using a liquid from of chlorine and he encourages the use of (expensive) lithium hypochlorite instead (or pre-mixed Cal-Hypo in a bucket). It is true that concentrated chlorine is more dense than water so will migrate towards the bottom if you just dump it in quickly, but when diluted (hitting the return flow, for example) it should lower in density close to water and not "settle". Until I get this sorted out, you should be very careful -- and could even pre-dilute the liquid chlorine in a bucket of water and pour that slowly to be even more safe. Also, pouring very slowly into the skimmer might be OK as another alternative.

At some point, I'll do some experiments in my pool with these two chlorine sources and see if I can measure the dispersion rate of the chlorine from one end to the other. The Lithium Hypochlorite probably is safer not only because it dilutes very quickly but also because it can be applied over the large surface of the pool and not in one place (though on a windy day I'm not sure how well that would work out). However, I am not yet convinced that there is no safe way to add bleach or chlorinating liquid. My hunch is that it is the improper application that is the problem, but we'll see (I've been wrong before, of course).

Richard