In our last blog, we addressed the problem of persistent cloudy water that does not respond to normal solutions such as use of clarifiers and other typical chemical solutions. For the most part, persistent clarity problems are much more common with sand filters and to some degree with cartridge/element filters. OK, so if you have a cloudy pool and are having a hard time seeing the bottom, what is your next step? Last week we addressed a filter aid designed specifically for sand filters, called Sand Helper from OnGuard® Chemicals. If results are not where you need to be after this, or you do not have a sand filter, then Step 2 will be next. At EZ Pool & Spa Supply we prescribe the use of Alum in order to precipitate the fine particles out of solution and to the bottom.

Alum, short for aluminum sulfate, is a flocculant, meaning that it attracts and traps suspended particles in the water and then sinks them to the bottom of the pool so that these particles can be vacuumed out. Quite often after using alum most pool owners will find the water to be crystal clear with the exception of a solid layer of the chemical and particles on the very bottom of the pool. The use of alum is more labor-intensive but often gives quick consistent results.

How to Effectively Use Aluminum Sulfate in your Swimming Pool

So here’s how you’ll use alum in your pool:

1.) If the water level is a bit on the low side, add a bit from the tap to bring water up a bit higher than normal,

2.) Test water pH and use a pH Increaser to bring the water’s pH up to about 8.0 – this is critical in getting alum to perform at its best. (Raising pH alone will help bring some of the particles suspended in the water out of solution, dropping them to the bottom.)

3.) Run in normal “filter” mode for 1-2 hours after adjusting up pH.

4.) Shut the filter off – this is also very important!

5.) Broadcast over the surface of the pool as evenly as possible at the rate of 3-4 ounces per 1,000 gallons of pool water.

6.) Wait until morning and vacuum pool with multiport valve set to “waste” or “bypass to waste”.

7.) Add more fresh water as needed and adjust pH if necessary.

Keep in mind that this is not just a pour-in-and-done product and will involve vacuuming and re-vacuuming, as the debris that settles to the bottom will likely stir up as you try to remove it. Don’t lose heart, but just wait for it to settle and hit it again!

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