Closing tomorrow and I have some questions about polyquat

[nadar]

My pool boy is coming to close my inground pool tomorrow. He recommends that I put an algaecide into my pool even though my water temperature is 61 degrees because we tend to have mild winters. He recommends a copper based algaecide but I told him I'd rather use polyquat since it is nonstaining. I've been reading about polyquat on here and it concerns me to use it because it has to be applied when chlorine levels are normal and it can reduce chlorine levels after it is added to the water. I also read that there is no need to add more chlorine if it goes down after adding it, and it can reduce chlorine levels further a day or two later. If I add it to my pool tonight at my normal chlorine level and it lowers my chlorine level down to 1 ppm or even 0 ppm a day later after my pool is already covered and closed, is it going to protect my pool from algae the rest of the fall, winter, and early spring? If I tested my water after closing and found that the chlorine level is 0 or really low, I don't have an easy way of adding more chlorine or algaecide since I don't own a pump.

I also need to know the best way to add the polyquat to my pool and the dosage. I'm going to have to vacuum my pool and backwash right before closing since leaves are constantly dropping into my pool, so I need to know if I need to add a little bit extra since I will be losing some of it to backwashing. I also need to know what the PH needs to be before it is added since I probably have a PH of 7.8 right now.

 

[tim5055]

Have you seen this in Pool School - Table of Contents

Pool School - Closing an In Ground Pool

 

[Texas Splash]

Your concern about chlorine oxidizing/consuming the Poly 60 is understood, but this applies more so when the FC level is exceptionally high (i.e. performing a SLAM). The high chlorine simply oxidizes the Poly reducing its effectiveness. Your FC level should never go to zero (at least not early on), regardless if you use Poly or not. So if you are not doing a SLAM at this point, and believe your water to be clear and free of algae or other material, then simply make sure your FC and CYA are properly balanced according to the [FC/CYA][/FC/CYA] and add the Poly 60. Let it circulate for an hour or so while you prepare other areas of the pool for closing and you should be fine.

Polyquat should be added like most chemicals near the return jet(s) slowly. You can brush it around a bit as needed to help circulate. Follow the dosage amount instructions on the bottle. Refer to the TFP closing procedures Tim posted above and you should be in good shape. As always, open as early as you can next spring before the water begins to warm up and organic matter becomes more active.

 

[nadar]

Your concern about chlorine oxidizing/consuming the Poly 60 is understood, but this applies more so when the FC level is exceptionally high (i.e. performing a SLAM). The high chlorine simply oxidizes the Poly reducing its effectiveness. Your FC level should never go to zero (at least not early on), regardless if you use Poly or not. So if you are not doing a SLAM at this point, and believe your water to be clear and free of algae or other material, then simply make sure your FC and CYA are properly balanced according to the [FC/CYA][/FC/CYA] and add the Poly 60. Let it circulate for an hour or so while you prepare other areas of the pool for closing and you should be fine.

Polyquat should be added like most chemicals near the return jet(s) slowly. You can brush it around a bit as needed to help circulate. Follow the dosage amount instructions on the bottle. Refer to the TFP closing procedures Tim posted above and you should be in good shape. As always, open as early as you can next spring before the water begins to warm up and organic matter becomes more active.

Thanks for the tips. I have a few more questions. Will Leslie's Algae Control Work and do I use the visible algae dose which is 11-16 oz per 10,000 gallons or the clean pool dosage which is 6-11 ounces per 10,000 gallons? Do I wait to add it once my FC is at my target level for my CYA, which is 5-7 ppm? Do I need to lower the PH before adding it since it is 7.8, and if so, how long do I have to wait after adding muriatic acid before I add the Polyquat? If it ends up lowering my chlorine level overnight, is there any harm in adding more chlorine to get to my target back up to target level before closing?

 

[Texas Splash]

I'd stay clear of Leslie's unless the algaecide they sell has the ingredient listed as Poly [oxyethylene (dimethyliminio) ethylene (dimethyliminio) ethylene dichloride]. You don't want to add anything else. As for the dosage, you would hope to add what is required for a clean pool. If your pool is dirty, shows signs of algae, or seems to fail an Overnight Chlorine Loss Test, you may open to a green pool next spring no matter what you do or add. Ideally the water needs to be clean & clear. If that means doing a SLAM now and closing with an elevated FC without the Poly, so be it. But if your water is good now, then add the Poly and it should help get you past the next few months with minimal problems next spring. You want the FC balanced at your normal target level when adding the Poly. The TFP closing instructions show lowering the pH to about 7.4 before closing to help account for the slow pH rise in colder water. So add the acid, let it mix for about 30 minutes or so and re-test. Add the Poly last once everything is verified and done. Once you add the Poly, we assume the FC was already where you wanted it, so simply close and enjoy your winter. :gone: Don't bother going back and re-testing or adding chlorine later. If you go back & forth you'll probably just drive yourself nuts. But again the key is clean & clear at closing. If you're not sure, do an Overnight Chlorine Loss Test if you need to. If your water temp is at or below 60 now, organic activity is coming to a halt already, the OCLT may not show much FC drop anyways.