Water Balance Question

[ssmith579]

I've recently moved into a house with a pool! The pool has an SWG but the owner says they didn't use it. I had the water tested and came up with the following:

FC - 5+
PH - 7.6
TA - 170
CH - 630
CYA - 80
TDS - 2500+
Salt - 2500

I want to use the SWG so I know I need to raise the salt to about 3200. I'm adding acid to try and get the TA down to a reasonable level. Should I be concerned about the high CH? I think the owner just dumped a boatload of chlorine in the pool before I moved in. I've been there a month and haven't added any yet.

Thanks,
Steve

 

[duraleigh]

At first, I wouldn't do much other than turn on the SWG.

It certainly wouldn't hurt to lower your pH with muriatic acid and keep it in the 7.4 or so range (the TA will come down a little as well) but it's not that bad nor is TA at 170 unmanageable.

After you run the swg and have a little while to get a feel for your pool, you'll likely find your pH will constantly rise. Lowering your TA down to around 80 or so may help slow that down.

You cannot permanently lower TA (and not lower pH) with acid alone. You must use an acid/aeration process described in pool school "How to lower Total alkalinity"

 

[JasonLion]

Welcome to TFP!

You do have some risk of CH scaling if you let the PH go up, because of the very high CH level. Bringing both the PH down in the short run and the TA down in the longer run will help avoid any actual scaling.

 

[polyvue]

Should I be concerned about the high CH?

In line with the advice above, may I suggest that you try entering the test results into the Pool Calculator? You can play around a bit with the "after" column numbers and get a pretty good idea of what is required. It's also handy when trying to figure out how much chlorine or muriatic acid is needed. Lots of people here experienced with this application so you can post back with questions and get them answered.

 

[dawndenise]

Having moved around a lot, I'm always suspicious when previous owners tell me, "Oh, we never use XYZ appliance."

Watch the control panel of your unit for a few days after turning the SWCG on. With that high CH and an owner saying they "didn't use it," it wouldn't surprise me if the cell itself has mega deposits that need to be removed which will make some of your indicators flash.

If any issue does arise, I know there are LOTS of helpful people here to help you get it fixed.

 

[Strannik]

you should probably clean the cell before even turning it on

 

[ssmith579]

Thanks for the help. I'll pull the cell out and check it out.

 

[salinda]

Where are you located? I actually have similar numbers on CH but I have managed to get my alkalinity lowered over the years. I just buy muriatic acid by the case and put some in every couple of weeks or so in the winter and 1-2 times per week in the summer to keep the ph from spiking, which would cause scaling. The salt cell is easy to clean. Just get the manual online if you don't have it. You use the same muriatic acid as you will need constantly for your pool and you dilute it and soak the cell in it somehow. With mine (Zodiac), I just pour in a dilute solution. Actually I cheat at this point and mostly fill the cell from the hose and top it with a smidge of acid (it is supposed to soak 1:10). I soak for about 5-10 minutes, pour it out, rinse with the hose and repeat until it is pretty clean. Make sure you buy chemical resistant gloves and store them near your acid. I bought mine at the hardware store. Also remember that the salt cell probably won't put out much chlorine (it might not work at all) when the temp is below 65 degrees or so.

 

[ssmith579]

I'm in Ventura, CA. I've added muriatic acid and now the PH is at 7.2 and has been stable for a couple days. I plan on adding 160lb of salt per the pool calculator and then trying the swg once the chlorine comes down a bit. It's been over a month without adding any chlorine and it's still off the chart.

 

[salinda]

The chlorine won't start dropping until the sun gets stronger and the pool water temp rises. Just leave the leads to the swg unplugged if you have no other way of turning it off.

 

[dawndenise]

It's been over a month without adding any chlorine and it's still off the chart.

Remember that if your SWCG is off, you're running a "regular" pool. Without the SWCG on, your target chlorine level (FC) is actually 9 with a CYA reading of 80 (you mentioned in your first post that your FC was 5+ and CYA was 80). With CYA of 80, a minimum level of FC would be about 6. Of course you can always drop that a bit if your water temp is fairly cold. But my point is that your free chlorine may not be as far "off the chart" as you think. A FAS-DPD testing kit, such as the TF-100, or similar Taylor kits can help you better test FC readings over 5. :-D