First read - starting BBB


Active member
Jul 3, 2010
Double Oak, TX
Full history. This summer completes the 10th season of this pool. I am the only owner this pool has ever seen. I have always maintained the pool following advice of trusted pool supply store - no pool maintenance services. I have always used 3" pucks until this last summer when I switched 1" pucks for a chlorine floater. And I use granulated chlorine for shock (sodium dichloro-s-triazinetrione dihydrate). My pool has been clean & clear over the years, though I experienced some problems with pH & clarity this year. I also have problems with calcium scale, I fear. The water today is crystal clear.

Having said all that, here are the numbers.

FC - 0 (I expected this - not worried)
pH - 7.2
TA - 110
CH - 475
CYA - 150+

CYA not most accurate read. I blocked out the black dot at the 1.8ml line on the small comparator tube.

I've reviewed the pool calculator & I understand the Chlorine & pH steps. TA, CH, & CYA numbers look really high. Advice & recommendations?



TFP Expert
LifeTime Supporter
Jan 6, 2010
San Dimas, CA (LA County)
Read Pool School

Order a test kit. Be sure to get the FAS-DPD kit. There's an article in Pool School explaining the differences.

Stop using stabilized chlorine now.

Plan to drain and refill the pool between now and next summer. If you expect a lot of rain, you can do it in phases. There ain't no other way to lose the excess CYA. It will also reduce CH.

TA will come down in time if you keep pH low.


TFP Expert
LifeTime Supporter
Nov 5, 2008
Where in Texas is Double Oak -- oh never mind, you are just north of Grapevine, near Dallas/Ft Worth. That answers my other questions...
Do you get good winter rains? Some. Are you on water restrictions in the summer? Yes.

You will need to drain and fill something like 50+% of the pool to get CYA down. Two ways to approach that. Either dilute a sample by 50% with distilled water to try to get a reading on CYA, or drain and fill the pool by some fraction maybe 60%. It may be that drain and fill will be enough, but it also may be that you'd refill the pool only to find that CYA was still 100 and you'd need to do it all over again which wastes half the new water you just put in.

Kinda depends on the water issues locally at this time of year and how long you want to mess with this. Being near the end of pool season, you may be able to just get close and let rains help over winter. To take advantage of free rain when you can lower the pool level by a little when a rain is expected. Then, after whatever rain you get, add tap water to the level you need. With 30" of rain a year you can't depend on rain to help you out much but when it is there it is good. But, you may find that in spring the CYA and CH have both fallen some. Then in the spring you can get it all fixed.

Personally, I think I'd try to get it right in one shot by testing with dilution first.

I am also interested in what your TA and CH of tap water are.


Active member
Jul 3, 2010
Double Oak, TX
I'm bumping this back to the top. It was near end of season & I was near end of product, so I delayed my transition. I'm prepared to start transition this weekend. Any suggestions about the extent of the pool drain? 50%? 75%? 90%? I presume that using the pool pump backwash channel is the proper way to drain? Thanks.


LifeTime Supporter
Jul 3, 2008
Solon, Iowa
The simple answer is drain and refill in stages, testing CYA after each refill, until your CYA reaches your target level. In order to get a precise answer to your question, you'll need to accurately determine your CYA level using the dilution methods suggested earlier (since the CYA 'dot' test isn't accurate for readings above 100).


As the "anti drain" guy, it hurts me to say this, but I would drain the whole thing and start over. To me, there is no good reason to do it in steps, as it just prolongs the process. Drain it, fill it, and re-balance the chemicals.

Now if someone would get R/O going in Texas (our website gets the most hits from Texas, so I know you guys have "issues" with your water!) I wouldn't have to tell you to drain :evil: Some states really make me angry :lol:


Active member
Jul 3, 2010
Double Oak, TX
OK - Pool drain & refill complete. Drained 70-80% of pool. Just ran my tests - here are the numbers:

FC - 0
pH - 7.9
TA - 100
CH - 150
CYA - 63 to 65

I'm a little disappointed in the CYA number when compared to recommended numbers. I'm not prepared to drain again right now to reduce CYA.

I have chosen these target chemistry numbers:

FC - 4
pH - 7.6
TA - 80

Using the pool calculator I apparently need: 3 jugs of Clorox bleach, 29 oz of muriatic acid. Open to direction & correction here. Thanks.


TFP Expert
LifeTime Supporter
Apr 4, 2009
With CYA at 60+ your FC target should be around 7ppm with 5ppm being minimum on a non-swg pool. Other than that, looks good.
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