Winter Pool Algaecides

winter-pool-algaecidesYou may not think too much about which algaecide you put into your pool for the winter. If you use a winter chemical kit, and everything seems to work just fine, there is no cause for pause.

For others, who may wonder which algaecide to use when closing the pool, this blog post is for you.

Winterizing Pool Algaecides

Algaecide 60 Plus:

Algaecide 60 PlusLikely the most commonly used winter algaecide, Poly 60, and it’s diluted cousin Poly 30, are stable in cold temperatures, and able to withstand fluctuations in pool pH levels better than other pool algaecides.

“Poly” means Polymer, which describes the chemical formulation of this particular algaecide. The number 60, or 30 – refers to the percentage of polymers; Poly 60 is a 60% solution.

When using a polymer algaecide for winter, it’s important to add the algaecide separately from winter pool shock. I would recommend that you shock the pool 1 week prior to closing, and add your poly algaecide just before you cover the pool.

Winter Pool Algaecide:

Our Winter Algaecide has been a customer favorite since we introduced it in 1984. It’s a special blend we created specifically for pool closing. This polymer algaecide is buffered against degradation by high chlorine or erratic pH levels.

Added coagulants help to gather together suspended particles in your pool water, while the long polymer chains seek out and attach themselves to contaminants and algae. Once attached, winter algaecide destroys the algae cell by rupturing the cell membrane.

Long lasting, and treats up to 20,000 gallons. For best results, especially for mesh covered pools, add one bottle at closing, and another bottle when the outside air temperatures once again reach 60 degrees in the spring.

Other Winter Algae Treatments

No Mor Problems Algaecide: Algae control and clarifier in one, No Mor Problems is a proprietary blend of ingredients, which means that the contents are not specifically listed, however we do know that Sodium Bromide is one of the active ingredients, which plays well with chlorine.

No Mor Problems algaecide has some very strong reviews on our website, and some very loyal users. 1 bottle treats the average sized pool and may have you enjoying No More Problems!


SeaKlear Free & Klear: This is not actually an algaecide, and for winterizing, should be supplemented with a winter algaecide. However, it is worthy of mention in this blog post. Free & Klear is a blend of 3 effective pool chemicals; Enzymes, Phosphate Remover and Clarifiers.

If you have had repeated trouble with algae blooms this year, or are tired of your pool looking swampy when the cover comes off – you may benefit from an enzyme and phosphate removal chemical. Natural Chemistry makes a similar product; Pool Perfect + Phos Free.

In Conclusion:

To sum it all up, the best algaecide to use for winterization tends to be polymers. In addition to algaecide and balanced pool water, a floater filled with a non-chlorine sanitizer will help to keep your water fresh.

If you use a chlorine floater, be sure to tie it off, to position it in the middle of the pool, to help prevent it from tipping over, or coming to rest on a step or swimout.

Most pools should use a stain & scale preventative to minimize staining potential during the winter, by keeping minerals in solution.Winter Closing Kit

Of course, if you’d rather have “no cause for pause”, use a winter chemical kit – it’s by far our largest selling winter pool chemical!

Till next time…


Brett Rotelli
InTheSwim Staff Blogger

Leave a Reply

Your email address will not be published. Required fields are marked *