Shock with Bleach

[Pool in Carolina Blue]

Thanks for the great information on this forum. I have a 5 year old 23,500 gallon in-ground pool. I am in the process of switching from 3" trichlor pucks (from my in-line feeder) as the primary source of chlorine to bleach. I have some pucks left and want to utilize them before switching to bleach as the primary source of chlorine.

Can I shock with bleach in the interim period while I am still using pucks in my feeder? Thanks for the feedback.

[Spensar]

Sure can. It's all chlorine.

[KurtV]

Carolina,
What's the CYA level in your pool? If it's very high, which it almost certainly is, you may not want to make it even higher by continuing to use trichlor. Also, if you haven't already done so, consult Ben's Best Guess Table to see what level of chlorine you need for normal sanitatizing and shocking.

Don't pour bleach into the skimmer as doing so can cause your chlorinator to explode. This can happen even if you don't have any pucks in the feeder.

[Pool in Carolina Blue]

KurtV:

My CYA is right at 70. I inherited this pool when I bought this house a year ago and had a pool service for the past twelve months. They were not doing a good job and we had a continuing problem with algae blooms etc. Since I "took over," things have been fine the past six weeks. I have been very diligent on testing and have been using one of the local retail stores for supplies (pucks, shock, etc.).

My current readings are:

FC 3
TC 3
PH 7.8
TA 150
CH 300
CYA 70

I have consulted Ben's table and have also downloaded the Bleach Calc program. I have also bought the BBB's and am ready to roll! Thanks for the help!

[KurtV]

Remember that your free chlorine should be between 5 and 10 ppm with a CYA level of 70.

Your alkalinty is pretty high. Does your pH drift up steadily? If so, you might want to lower your alkalinity (the procedure for doing that is here). You might want to start a new thread in that forum to seek advice on a target level.

Other numbers look good. It's obvious from your questions and responses that you've been doing your homework.

[Watermom]

Is this a vinyl pool?

[Pool in Carolina Blue]

KurtV:

My pH does drift up so I have been using small amounts of pH minus to bring it down once a week or so. I have been keeping the chlorine level at 5 or higher (the Taylor kit only reads to 5) and the 3 reading yesterday is the first time I have seen it dip below 5 since I took over. Thanks for the link on the alkalinity as that might be a solution.

[Pool in Carolina Blue]

Watermom:

This is a gunite pool. I added bleach last night and brought the chlorine level back up the 5 when I tested this morning.