Closing a salt water pool is a little different than closing a regular chlorinated pool. The first thing you should know is that while your salt water generator works great in the summer with the warm water, when water cools down it affects how the system may read. It may tell you the pool is low on salt when in fact it is not.
BEFORE YOU CLOSE A SALT POOL
LOW SALT LEVELS: It's always best to double check your salt level by using salt test strips for an accurate reading. When the season starts cooling down do not add any more salt to the pool if you can help it. I recommend you shock the pool a week prior to closing the pool, using powdered pool shock, not your salt chlorinator. Use 1 lb per 10K gallons, pre-dissolved into a bucket of water, and poured around the edge of the pool. As you reach the last weeks of your pool season, we do not want to have a lot of salt in the pool, it's better to have it on the low end of the range. This is because salts in the water can react with contaminants in the pool to form winter pool stains.
BALANCED WATER: The second most important thing to do before closing a saltwater pool, is to make sure the water is balanced. Check and balance the pH, alkalinity and calcium hardness levels.If your calcium hardness level is high (over 400 ppm), be extra careful to keep a pH below 7.6 during winter by checking it every so often. As the temperature of the water drops lower during the winter, and there is no circulation, it's easier for salts to form crystals, if pH, alkalinity and calcium are not kept in check.
CLEAN POOL: The third most important thing to do is to thoroughly clean the pool, spotless. This is important for any pool, but especially those that carry the extra load of salt dissolved in the water. If your winter pool cover does not fit tightly, make a clean sweep around the pool every few weeks, to keep as much leaves and debris out of the pool area as possible during the winter.
STAIN & SCALE: Fourth step is to protect against stains & scale with a stain & scale preventative for metal and mineral control. Natural Chemistry has a great metal and mineral chemical called Metal Out. For heavy metals, use CuLator, which is a little package you throw in the skimmer that instead of just sequestering metals and minerals, it actually absorbs them and removes them from the water. Always let the pool filter run a good 8-10 hours after adding the mineral and stain remover. This ensures that the product is circulated well before closing the pool, because stain & scale chemicals do their protective work right away, within hours.
ENZYMES: Finally, for pools with a mesh cover, or solid with drain panel safety cover, I would add the “winter ball” or a similar enzyme product. This is a slow release product that will keep your pool protected from stains by ingesting oily gunk that gets into the pool. Oils + Salts = bad news, that's why if you do nothing else, (and you have a safety cover), I suggest using a winter pool enzyme, to prevent winter pool stains on a salt pool.
AFTER YOU CLOSE A SALT POOL
1. While the pool is closed do not add any salt. Remove and store the salt cell indoors.
2. it is always a good idea to test the water every 6-8 weeks during the off season to ensure the H, alkalinity and calcium levels are OK.
3. Keep the pool cover clean. Mesh safety covers require a little more attention than solid covers. If the wind isn’t blowing the leaves off the cover, use a broom or blower and blow them off. If you have a mesh cover keep the water level a few inches below the tile, and tighten the cover if needed. Pool noodles or water bags can be used around the edge to prevent leaves from blowing under.
4. I also use a floater in the pool which releases chemicals slowly into the water to kill germs and algae. Use a non-chlorine floater, so if it tips over or comes to rest on a step, it won't stain the pool.
In summary, for those of you that use a salt chlorine generator, and also winterize the pool - there are some concerns about the salt coming out of solution and forming stains, due to the cold temperature and the non-circulation. Preventing stains in your pool this winter, vinyl or plaster, is easy when you apply the right methods.
SPP Pool Expert