No matter what type of DE filter you have (in my case it’s a Hayward DE40), you have to make sure you add the proper amount of DE. Adding too much means the DE will end up back into the pool and adding too little will prevent the filter from running at its best.
If you don’t know this already, use caution when breathing around diatomaceous earth. The fine particles that do such a good job of cleaning out your pool can reek havoc on your lungs. DE likes wet linings to adhere to. Therefore, it is recommended that you use a protective mask when adding DE to your filter. I sometimes use a mask, but more often I pull my T-shirt over my nose and mouth as a precaution while holding my breath until I’m done pouring it in the skimmer (not very professional but it works).
How much DE to use?
Well, I have a very tall cup that we got from an outing to an amusement park. I fill it 4 times with DE and pour it into the skimmer. When I first started I used to pour the DE into a bucket, add water, stir and then slowly pour it into the skimmer. I guess that worked, but it took too long and involved too many processes.
Eventually, I bypassed the bucket, mixing it with water. I now pour the DE directly into the skimmer a little at a time. I wait until I see it clear the pump impeller basket and then add a little more. Again, not very scientific or professional, but it works. I think the manual recommends 4 pounds (which is more or less the amount I put in using my amusement park cup).
Now that my filter is properly coated with DE, it’s time to really work on learning about pH, chlorine, shock, algaecide and any other factor necessary to make a pool’s water clear.