Extreme pump pressure

[JohnT]

One of the downsides of DE filters is they clean so well they have problems with getting dirty trying to clean up an algae bloom. If the pool is still green, you haven't killed the algae yet.

Two ideas:

Have you cleaned the grid by soaking in whatever the manufacturer recommends? The grid can get dirty enough that routine brushing won't clear it up.

Are you sure you are adding enough DE after you backwash? Not adding enough DE will cause the filter to clog, and backwashing won't clear it.

As long as the algae is alive, there is no end to what the filter has to remove. Getting the algae killed is the first step, and if you have to run the filter on recirculate until that happens, that's okay.

[poolgal]

We hose off the grids to clean them. They come out as clean as they usually do, so that doesn't seem to be a problem. Also we put in 9 cups of DE which is also the same amount as normal.

Unfortunately, we don't have a recirculate option. Our system only has backwash or filter, so recirculation isn't an option for us.

We dumped in a bunch of algae killer, but I guess it didn't fully work. Looks like bleach is good for killing algae. How much should we use in a 10kgal pool? Our test kit can't test very high levels of chlorine.