testing results

[smallpooldad]

pH of 7.3 ok
Alk 120 ok
FC 5 ok
CYA 60 ( too high go to 45 by draining down the pool 25%. This should keep you algae free but if you are not getting algae at a CyA of 60 it is your choice)

[CarlD]

pH of 7.3 ok
Alk 120 ok
FC 5 ok
CYA 60 ( too high go to 45 by draining down the pool 25%. This should keep you algae free but if you are not getting algae at a CyA of 60 it is your choice)

Don't waste your time draining your pool! I hate to say it, but SmallPoolDad is wrong on this one.

There's nothing wrong with a CYA of 60. You'll have to keep your regular FC in the 5-10ppm range , but that's fine. IF you keep it there, you'll use less chlorine this summer as it's been a real chlorine eater all around! If you keep it in that range you won't get algae.

Our "Best Guess" table is still a great way to stay safe and compensate for higher levels of CYA. aylad, one of my fellow monitors, NEVER runs her pool below a CYA of 60--she lives in Louisiana where it's hot and sunny and the chlorine disappears if you blink at "normal" CYA levels. So she runs a higher CYA, a higher normal residual level, and doesn't go through barrels of bleach keeping her pool clean.

Using the "Best Guess" table give you the correct equalibrium between CYA and chlorine residual levels.

[smallpooldad]

I think I wrote drain it, if 60 is problematic - "but if you are not getting algae at a CyA of 60 it is your choice." If not I agree leave it alone. I think and agree that the way I wrote it was confusing.

Whatever, 60 is OK if there are no problems. At 45 CYA, way south of Louisiana, in Hawaii, we would also loose very little chlorine. It is just at 45 you are carrying a little more insurance as regards algae. But living on the edge is so much more exciting. Lower Cya means your chlorine is disinfecting more, it is as simple as that.

After 35 the difference in loss of chlorine is minimal in my experience but that seems to vary from geographic location and how much debris falls into the pool on a daily basis. Debris free and you should not loose too much chlorine at the lower CYA number.

Another advantage of lower CyA is that if you did have to shock with chlorine you would need less, see the "Best Guess" table, so why drive at 80 mph when you can get there at 30 mph, unless of course lower CyA truely does use up more chlorine, in your case, and indeed that might be - so then there would be no advantage at all.

If you are going for 60 CyA then I agree with CarlD that you should try to find the Optimum chlorine point where you have no trouble 5-10 ppm. Lowering the CyA lets you lower the Chlorine number somewhat. As he said look at the "Best Guess" table. Personally I prefer lower CyA (35) and lower chlorine(4-6) but to each their own. Ideally try to keep the CyA no higher than 80, or stretching 100.

Sadly as you are using pucks you will most probably have to drain it some if you wish to maintain 60 and not go above, unless you have a lot of kids jumping in and out of the pool doing it for you. If the CYA is allowed to go higher you will need to raise the FC amount. If you do drain at the end of you season (we have no seasons) you might want to consider starting at 35 and letting it float up to 60.

I am not sure how accurate the Wal-Mart kit is, others may wish to comment. If they state it is not accurate you may wish to get a Taylor Test Kit, for the added assurance you have the right numbers.

What you are looking for is a clear pool with a glassy surface, like the magazine pictures. It seems that you are pumping for the correct amount of hours based on your pool size assuming a correct sized pump and filter. If it is not clear look to either a lower CyA, assuming the chlorine loss is not too great or expensive, or a raise to a higher chlorine level.

[waterbear]

Whatever, 60 is OK if there are no problems. At 45 CYA, way south of Louisiana, in Hawaii, we would also loose very little chlorine. It is just at 45 you are carrying a little more insurance as regards algae. But living on the edge is so much more exciting. Lower Cya means your chlorine is disinfecting more, it is as simple as that.

IF you are running the proper FC levels for your CYA it's immaterial. Here in FL we often run pools with a CYA of 60 because of the amount of sunlight. In areas like Arizona, which also get extreme sun high CYA levels, high CYa levels are common (I've heard of levels in the 80-100 range in manually chlorinated pools). As long as the FC level is raised to compensate for the CYA there is no problem and some resent research seem to indicate that CYA actually has some direct UV blocking abilities to protect the chlorine at deeper levels.

You speak of your experience with your pool. The collective experience in this forum is with MANY pools. (And my own experience is also with many pools since I do work in the industry.) Perpective is a good thing.

[aylad]

My pool is currently at CYA of 80, which is where I tend to run it year round. With my temperature and humidity conditions, and the fact that my pool is in full sun literally all day, any CYA lower than that and I cannot effectively keep it chlorinated. At a CYA of 80, my chorine consumption has drastically dropped, and I only have to add it a couple of times per week. So....each pool is different, each climate is different. It's a matter of finding what works for your pool and sticking with it. Minermom's numbers to me look good, and as long as her pool is clear, looks to me like she's doing a great job.

Janet

[smallpooldad]

Hello Waterbear,

Here are the US Government’s numbers for the mean UV index for July (see here

http://www.cpc.ncep.noaa.gov/products/stratosphere/uv_index/gif_files/julavg.gif

Honolulu is 12, Phoenix 10 and Miami 9; my CyA at 35 sure works well with FC at 6. As stated we have minimal loss of chlorine.

Agreed that you have more extensive experience than I; and I really appreciate you taking the time out of your busy schedule to answer my posts. But the question still remains why a CyA of 35 in Hawaii with our elevated UV performs just as well as 60-100 CyA in states with lower UV?

Could it be that as Chem Geek pointed out there is minimal difference in chlorine loss after one reaches 35, do you think he is right, or possibly wrong?

Please note our mean UV index in August is 12 versus the other locations which are 9. In September our UV remains at 11, when the other locations drop to 7 or 8.

I agree that I am religiously following the water chemistry dictated by the "PoolEquations" spreadsheet but it is working for me.

pH 7.5
Alk 80
CyA 35
Calcium 425
Boron 50
Salt 3500

Please let me know what you think as I am no scientist. Maybe I am misinterpreting the datum.

Thanks again for your help.

[waterbear]

You have not been keeping up with Richard's(Chemgeek's) lastest posts (then again I don't think you are a member at TFP), Recently he has some evidence that higher CYA levels offer more protection to chlorine than formerly thought. You have a CYA of 35 because you are using ORP control for your SWG, correct? If you were not you would seel the better chlorine retention you would get from a CYA of 70-80 ppm but becuase that would play havoc with your ORP controller it is not meant to be.

Once again, I say that your experience is with one pool. You have posted quite a bit of misinformation and was even called on it by one of the mods in this forum. I have answered many posts for your because you were not sure of the chemistry that was happening. Because you have a spreadsheet that you take as the gospel (it is merely a tool, btw) and have a basic understanding of how to run a pool (most of the time) doesn't make you an expert any more than being able to carve a roast makes you a surgeon.

Now if you are finished with this thread hijack we can get back to the OP and her questions.