questions about adding polyquat or closing at shock level


Active member
Oct 21, 2018
Northern Tennessee
I have been managing my pool the TFP way this past year and I've read the information on here about closing an inground pool. A pool professional is going to close my pool on Wednesday since my water is now below 60 degrees. Last year, he put in a copper algecide that stained my pool so I'm not going to let him add any chemicals this year and prepare the water for closing myself. I've read the information on this site and I'm having a hard time deciding whether or not I should close at shock level or close at normal chlorine levels with polyquat. To help me make this decision, I have a few questions that I'm hoping one of the TFP pros or experienced pool owners on here can answer for me.

1. If I decided to use Polyquat 60, directions on here say that it has to be added to the water at my normal chlorine level which is 7 ppm, and several posts say that it will decrease chlorine levels after it is added. If it decreases chlorine levels by half or more and we get some warm days this fall or winter, will the polyquat protect my water from an algae bloom? If it decreases chlorine levels a lot, can I add more chlorine before closing or will this oxidize the polyquat and make it ineffective?

2. If I decided to close at shock level instead (which is 24 ppm), would the high chlorine levels over a long period of time damage the walls or floor of my fiberglass pool, damage my mesh loop lock cover (which already has a few small holes), or damage the grass when all of this heavily chlorinated water is pumped into my yard when it is drained before closing?

3. In years past, my pool pro has added Pool Magic Plus Phosfree right before closing since my phosphate level is always high prior to closing because of all of the leaves that fall into my pool this time of year. Is this chemical necessary and/or helpful, and is adding it right before closing while only running the pump a few minutes the correct way to add it?

4. Since my pool closing is scheduled in 3 days and there isn't enough time to get my pool to shock level and back down to normal levels, should I just increase my shock level to 10-12 ppm instead since my CC is less than .5 and water is clear? Pool is consuming only 2 ppm of chlorine right now because the water is so cold so if I shock to 24 ppm tonight, the water will only be 20 ppm in 2 days when the Polyquat would need to be added, which is too high.

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
nadar, with closing almost upon you, you have two choices really: 1 - Increase to SLAM level if you feel there may be a need to resolve any possible residual organic material and don't use the Poly; or 2 - Leave the FC alone if the pool is algae free and add the Poly. It's really a personal choice. Owners across the country do it both ways. The fact that the water is cold is priority #1 and it sounds like you're in a good place there. Now if you do decide to increase the FC, it should be fine on the shell and cover as long as the CYA level is correct to support/balance that FC level as noted on the [FC/CYA][/FC/CYA]. As for the Phosphate products, I wouldn't recommend adding any from the pool store as those products tend to be weak and costly with less than desirable results. We're not convinced their use is beneficial to this point either. If you chose to add some, that's certainly your prerogative, but consider obtaining a commercial grade strength phosphate product as opposed to the convenient store products.


Platinum Supporter
TFP Guide
Jul 30, 2014
Monmouth County, New Jersey

I am an advocate of using Poly60. No need to concerned about chlorine consumption, how much, and if you should bring it up. The pool being closed does not need chlorine (at least not too much), and the algaecide is designed to stall algae until the real cold weather sets in.

Although, in your situation, I would recommend against (not using) Poly60 for the closing. If your pool is clean (You should know as you would have had to test during the summer), then bring up to SLAM and close the pool. It is late in the year and the water is real cold, therefore not really needing the product. It is les expensive to add liquid chlorine at this point. Make sure the person who is performing the pool closing does not add any more chemicals.

As Pat mentioned, the priority is to close and open when water is 60 degrees or lower. The algaecide is highly recommended for early closings as sometimes pool owners just can not deal with a ton of leaves, debris, or just maintaining the pool longer than they want. You are all set.

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Active member
Oct 21, 2018
Northern Tennessee
Thanks for the advice. I'd love to save some money by skipping the polyquat and adding chlorine at shock level but it concerns me to close with a chlorine level of 24 ppm because I don't want to do anything that could potentially damage or bleach out my expensive green mesh loop lock cover that already has a few tiny holes in it. Since my water is already less than 60 degrees, I'm assuming that the chlorine level will stay high for quite some time and I'm wondering what impact that could cause for my cover. I assume that I could close at a lower chlorine level to minimize impact on my cover and add some more chlorine in March but I really don't want to mess with this since the loop locks are so hard to get on and off and readjusted properly. If I spent the extra money on the polyquat, would it give me more protection against algae for a longer period of time if we happen to have a mild fall, winter or spring than closing at shock level would? Or could I close at a lower chlorine level than 24 ppm and still be protected against algae until the last week of April or first week of May without having to add any more chlorine later? I know that I'm probably going to open up to some algae no matter what I do, but I want to prevent opening up to dark green water like I did last year since it caused some stains that were difficult to remove.