High CC and CH in New Pool

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New2TX

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May 3, 2009
5
I'm a newbie to both TFP and pool ownership. TFP has been fantastic for getting us up to speed on the ins and outs of pool chemistry - THANKS!! We just filled our brand new pool (16K in ground, SWG) two weeks ago and put salt in early this week. For the first week I was running OTO Chlorine, pH, and TA with the kit supplied by the PB. TA started out at 110 so I spent a few days reducing TA by the standard 'reduce pH/aerate' method. This morning the TA was down to 70 - score one for TFP...

My TF-100 kit arrived today, so now I can do better numbers (as a former chemist, I'm all for good numbers):

T 79 deg.
pH 7.5 (this has been going up and down as I've been lowering CH)
FC 5.5 (I got a little frisky with the chlorinator as the pump was running continuously during TA reduction)
CC 2.0
CYA 60-70 ( I added for 80 ppm three days ago, so this may still go up)
TA 70
CH 410
salt 3700 (reading on the SWG unit)

The water looks and feels great, but I'm concerned about the high CC level (the test result is repeatable). Is this normal for a new pool, or is this indicating some problem? Will CC go down as things stabilize?

I'm also wondering if I need to worry about the CH level, although since they had to pound through limestone for 3 days digging my hole, I'm not surprised. Can I figure that normal rain dilution will eventually take that down to more normal level? Dilution is my long-range plan for getting the salt down a little as well.

Thanks for all of your help to this point and into the future!
 
Welcome!

You're off to a great start. It's easy to tell from your post you have a grasp of all the concepts and are on your way to getting everything nearly ideal.

That CC of 2 indicates the need to shock. I am mildly puzzled by that result. Mostly because your water is clear and I see no past history of water issues so I would've expected .5 or less CC.

However, that's exactly why testing is such an essential part of BBB.....it will often ward off developing problems before they get a good grip in your pool.

So, I would shock. Not with your SWG but with chlorine (Bleach is probably the simplest to find) You'll need to put a dosage of chlorine in your pool to bring it up to around 20+ppm and then KEEP IT THERE until your CC's drop to .5 or less. In your case, I think that will be rather quickly but you must keep your FC up very high to eliminate the CC's from your pool.

Use Jasons calculator to figure your chlorine dosage.
 
Thanks Dave,

My problem is that I'm having people over on Sunday, and I'd like to have the pool swimmable, so I don't want to start shocking until Monday. If I start shocking on Monday AM, is it likely that by Wednesday night things will be stabilized? Once you're done shocking, do you just let the FC level reduce by itself? If I leave the SWG generator off, how long would that take at CYA=80?

I leave Thursday for 3+ weeks - my wife will be here to do minor cleaning, but she doesn't want to have to do a crash course in chemistry (all things in time). I'm having a guy come once a week to make sure things don't get out of control while I'm gone. If I could get CC to 0 before I go I'd feel better about leaving the SWG running and assume that things will be OK.

I realize that without knowing what's causing the high CC, it's hard to answer the question of how long shocking will take, but is 1 or 2 days what's typical? I'm confused, too, because the pool is brand new and I don't see anything that should be causing this. Water looks very clear. I'll test again in the AM.
 
CC higher than 0.5 is not considered swimmable. CC is normally fairly irritating at levels higher than 0.5, though there are exceptions. If you just filled the pool, then the CC might be from your tap water. Many municipalities use a form of chlorine that reads as CC to sanitize their water. In that case they will be using the non-irritating version of CC, and it will clear up quite quickly.

The CH level is not an immediate problem, but you do need to keep your PH from getting very high while your CH level is that high.

I suggest raising the FC level up to 10 this morning, and if the CC is from your tap water, it should be gone by tomorrow. FC of 10 is the top end of the normal swimming range given your CYA level.

It can take several days, sometimes more than a week, for FC levels to come down from shock level when CYA is that high. Most of us consider any FC level below shock level as being safe to swim in, though that is a judgment call.

You should show your wife the forum. If she has any problems while you are gone we can help her out.
 
OK, I tested my fill water this morning and sure enough, the CC level is 1.5 to 2! The pool sat overnight (no pumping, no SWG) and the FC and CC levels are essentially unchanged, so both pieces of data make me feel much better.

I'm off to the store to get bleach - I'll raise the level to 10 as suggested and we'll see what happens.

Do I need to keep the pump running the whole time I'm getting rid of CC, or should I run the regular cycle? I'm currently running 4 hours in the morning and 4 hours later in the afternoon (when the most direct sun hits the pool).

Also, while the FC is high, I might as well just leave the SWG off until the FC level gets back down to normal, correct?

Thanks for all the help!!
 
Plan B...

If the CC level is due to the fill water (and not irritating), then the water is presumably nice and clean and sanitary. What's the down side to just letting the SWG maintain the FC level at 5 have the existing CC get chewed up over the long term - I'm going to be up in the middle of nowhere Canada fishing for 3 weeks, and when I get back, the CC should be gone, right?
 
If you are not swimming it doesn't make any difference. But if you are swimming, it is better to have CC at zero so that the tap water CC doesn't mask any irritating CC reading. Plus, the CC is going to create a little extra FC demand, so it is best to boost the FC level a little higher than normal right now so it doesn't get too low at any point.
 
So that brings up a question about proper FC level. Pool School says 3-5. My SWG and PB say 1-3. Of course, I believe Pool School, but why the difference?

Also, the Chlorine/CYA chart recommends FC=6 for CYA= 80, and Pool School recommends 80 for CYA. so is 6 correct, or 3-5?
 
There are actually two Chlorine/CYA charts, if you look at the second one, which is for SWGs, you will see that the recommended FC level is 3-6.

It is possible to maintain a pool with a SWG around 1 to 3 for a while, but we have found that you will eventually have problems. Our recommendations are designed to work reliably, ie to be Trouble Free. Pool stores like it when you have problems, that means you come in and buy more expensive chemicals from them.
 
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