• 0Cart
    • Showing 0 of 0 item View All

      Estimated SUBTOTAL* :  $0.00

      *Excludes taxes, handling fee, and EZ Pay Service Fee, if applicable.
    • Checkout
    Source / Promo Code:SPPPROMO(Edit)
    FREE SHIPPING Handling May Apply

    FREE NEXT DAY DELIVERY! See What's Available In Your Area

    The Complete Guide to Pool Closing Chemicals

    September 15, 2014


    Closing your pool - winterizing your pool that is, requires certain chemicals to keep your water fresh and clean during a long off season with no circulation or filtering.

    Use the wrong winter pool chemicals, or not enough of the right chemicals, and you could end up paying for it come springtime, in terms of algae, stains and days or weeks of lost summertime, waiting for the water to clear.

    Today's post is all about pool closing chemicals - descriptions of the various types used, how to use them, and what types of winter chemicals are best for your situation.

    Winter Pool Closing Kits

    ultimate-winter-pool-kitLet's start out with the winter closing kits - these are non-chlorine pre-packaged kits that contain the most commonly used winter chemicals. Order according to your pool size, in gallons, or combine two winter kits for larger pools.

    SPP winter kits contain non-chlorine shock, winter algaecide, stain preventative, a non-chlorine pool floater, and an oil absorbing sponge, as added prevention against 'bathtub ring'. For vinyl liner pools, a non-chlorine winter kit is the best way to go, to prevent fading and bleaching of your pool liner.

    The Ultimate Winter Kit contains two great products by Natural Chemistry, an all-natural stain preventer - Metal Free, and the very popular Pool Magic Spring & Fall w/ Phos-Free, an enzyme treatment that also removes phosphates, one of the foods most preferred by algae, to literally starve algae into submission. Full disclosure, The Ultimate Closing Kit is the one that I use on my pool.

    Winter kits are the only way to get our non-chlorine floater - they aren't sold separately. The powerful non-chlorine oxidizer is a proprietary blend of sanitizers, borates and enzymes to remove oils and carbon dioxide from the water, and allow the sanitizer to work most effectively.

    Winter Pool Algaecides

    Now, I may be wrong, but I do not believe that there is any difference between summer algaecide and winter algaecide, other than the label. But there are several types of algaecide that can be used, some stronger than others. Here's a run down of various types of pool algaecides that can be used as a winter algaecide.


    Algaecide: A Quaternary Ammonium algaecide of 10% strength - best for green algae.

    Algae-Clear: A Polymer algaecide of 20% strength - good for all types of algae.

    Algaecide 50: A Polymer algaecide of 50% strength - good for all types of algae.

    Algaecide 60+: A Polymer algaecide of 60% strength - good for all types of algae.

    Black Algaecide: A Copper algaecide with 11% elemental copper - good for all types of algae.

    Eclipse 3: A Copper algaecide with 13% elemental copper - also contains clarifier.

    No Mor Problems: A Sodium Bromide algaecide with 41% NaBro - good for all types of algae.

    Super Algaecide: A Copper algaecide with 7% elemental copper - good for all types of algae.

    Winter Algaecide: A Copper algaecide with 3% elemental copper - good for all types of algae.

    Any of these can be used for pool winterizing algaecides. Generally speaking, the more expensive an algaecide is, the better it will be. The one you choose, and how much you use may be related to your winter pool cover. If you have a solid pool cover in great shape, a cheaper or less potent algaecide can be used. If you have a mesh pool cover, or one that lets in sunlight and debris, a better algaecide will be a better choice.

    If you use chlorine shock to close the pool - it's best to shock a week before closing, so a very high chlorine level won't harm your cover - and, destroy your algaecide. If you shock with chlorine the day that you close the pool, wait about a month before adding the algaecide. Just squirt it under the cover in 3 or 4 locations. Another method is to shock the pool hard when you close, and wait until early spring to add your algaecide, about 8-10 weeks before you open the pool.

    If using copper algaecide, it's best not to overdose, especially with a plaster pool. Even though these copper algaecides are chelated, there is still a potential for copper staining, although the potential is much less for vinyl liner pools. Adding a stain preventative is advised (Stain & Scale chemical) if you use copper algaecides, summer or winter.

    Winter Pool Shock

    swimming-pool-shocks- Shocking your pool before closing is necessary to kill any 'undesirables' in the water. Let's face it, many people tend to drop their guard on pool maintenance in the last few weeks, so a good shocking of the pool is a good idea.

    Before you shock the pool, you should clean the pool thoroughly, so that your pool shock isn't wasted, attacking leaves and debris in the pool.

    Also make sure that the water is balanced, with special attention to the pH and alkalinity levels. If your pH is high on the scale, up to 80% of your pool shock could be wasted, or ineffective. Drop the pH level to the low side of the scale, around 7.2, and check that your alkalinity is in range of 80-120 ppm, for best results.

    For vinyl pools, non-chlorine pool shock is preferred. It's clean burning (leaves no residue), and won't harm your vinyl liner. Even for plaster pools, chlorine shock can be harsh to your pool finish. If you do use chlorine shock, be sure to pre-dilute it by pouring it into a bucket that is filled with water, and stirring it until dissolved. Then pour it around the edge of the pool, being careful not to allow any undissolved granules fall in the pool as the bucket empties.

    Dichlor shock is often used for opening pools, or during the summer, because it is stabilized from the sun, but there is no need to use this more expensive shock if you are adding it just before closing the pool. Regular chlorine pool shock, or non-chlorine pool shock (potassium peroxymonosulfate) would be the best choice for most pools, unless your pool cover lets in a lot of sunlight.

    Follow the label instructions, to add the proper dosage. If you have visible algae, double the dose, and then brush the pool. As mentioned above, it's best to shock the pool several days in advance of closing, so the shock won't attack your algaecide or your pool cover.

    Enzymes for Winter

    pool-enzymesIf you have a mesh safety cover, like I do - all sorts of pollutants, acid rain, pollen, tree sap and algae can wash into the pool all winter long. Pool enzymes seek out and consume oils and bacteria that can stain your pool walls and steps. And because they consume these contaminants, it frees up your winter pool chemicals to fight algae.

    In the Ultimate winter closing kit, a bottle of Pool Magic is included. You could also use Pool Perfect. These both contain Phos-Free, to remove phosphates in the pool. Another popular enzyme chemical for pools is the Winter Ball. Poke a hole in the ball, and drop it in the pool and it slowly releases the chemical during the winter.

    Especially if you're a bit lazy (like me) with the pool maintenance during the winter, an enzyme treatment will take up the slack. Even when I do not lower the pool water soon enough, and my mesh cover gets a wet spot in the middle, trapping leaves like a giant tea bag, I am always amazed at how clear the pool water is, without the brown tannins and pollen.

    I'm in the flight path for a lot of overhead air traffic, and before I started using this, I would have a sticky residue of pollution all around my liner every spring. Not anymore, not since I started using enzymes as part of my winter closing chemicals.

    Stain & Scale Chemicals

    sequestering-agents-for-pool-closingUsing a stain & scale preventative chemical is always a good idea when closing your pool, to prevent mineral and metal staining. This should be added to the pool before lowering the pool water, because it is important for it to be quickly and thoroughly distributed throughout the pool.

    Stain Away is a sequestering agent, or chelator, that keeps minerals and metals tied up in solution, to keep them from staining your pool during winter. For pools on a well, with high levels of iron, magnesium or copper, use Natural Chemistry's Metal Free, which keeps minerals in solution without adding any phosphates to the pool. A must if you have well water.

    For hard water areas, those with high calcium hardness levels (over 400 ppm), Natural Chemistry has Scale Free, also very useful for salt water pools, to keep sodium in solution, and keep it from mixing with organic matter during winter, which makes a pool look dull and dirty.  

    Well, that's about it for winter pool chemicals. To summarize, balance the pool water chemistry and shock the pool, and add a stain and scale treatment - several days to a week before you close the pool. Then add a good algaecide and a non-chlorine winter floater, and an enzyme treatment just before you put the cover on.

    Do not skimp on your pool closing chemicals - it's kind of a "pay me now, or pay me later" kind of thing. Close it right, and you'll have a much easier, faster and cheaper pool opening!

    Chris Low
    SPP Pool Expert  

    Blog Author
    People Also Purchased