new pool, shock with chlorine or trichlor


May 1, 2020
Finally got my 21' 54" pool up after two days of heat, sweat and cursing. This was a used pool and came with a chemical feeder. I've never had a chlorine feeder and want to use the trichlor pucks as our season is quite short here in the northern prairies so looking at end of May till about beginning of September for swimming before the snow comes in November.

My question is that i just filled the pool and want to know if i can use liquid chlorine to shock it then continue on with the chlorine feeder with the trichlor. Someone told me that you can't mix the two, but not sure if they meant that you can't mix them together in the same feeder or whether once the pool has liquid chlorine from pool opening shock, that you can't start using the trichlor.

thx for the help


Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
Laughlin, NV
Welcome to the forum!
There is no reason to 'shock' a pool if your FC is kept in the target range based on your CYA using the FC/CYA Chart
Regardless of swim season, it is pretty difficult to use trichlor for daily maintenance and meet the above.
You can add liquid chlorine to the pool water at the return (not into the skimmer) with trichlor in your feeder.
I suggest you read ABC's of Pool Water Chemistry.


May 1, 2020
thanks for the response. For opening the pool, i'll need to add more liquid chlorine than normal to "shock" it i would presume. That's the way i've done it according the to instruction label. Then i can keep the chlorine in check with the feeder. If i find that my CYA levels become to high, i'll switch over to the unstablized chlorine and ditch the feeder. I'll read the chem ABCs as well


Well-known member
Dec 31, 2019
Houston, Texas
If you just filled your pool with water, there is no need to shock the pool. If you follow the recommendations on this web site, you will never need to use that word or type of product again.

As mentioned above, add enough chlorine based on the CYA / chlorine chart above. If you have algae problems down the road, use the SLAM method. Good luck!