How persistent are flocculants?

[Charlie_R]

Dogs were in the pool again today, and I noticed what I thought was a bit peculiar. I literally watched the dust and dirt they normally drag into the water fall to the bottom. What I mean is within moments of them being in the pool, I could see the fine clay silt drop out of the water into the many wrinkles on my pool floor. I'm thinking this is a bit unusual.

Our water plant does use a floc in the beginning stages of treating our water supply, and I'm wondering if this could be the reason for what I observed today.

It was kind of cool to watch it happening, and does explain why I need to brush many times with the filter working to get the majority of this dirt out of the pool. Most often, I end up just letting it go and vacuuming every couple of days. When I do vacuum, it stays in the filters, with little to no residual escaping back to the pool. I've even checked this with coffee filters on the returns, which come out clean.

Can anyone shed some light on this? I thought the usual routine with floc use was with the pump off, after circulating for a set amount of time to give it a chance to mix into the water. This was happening with the pump on, and good circular flow in the pool.

 

[Charlie_R]

With further experimentation, it appears the phenomenon appears to be more pronounced with the use of my aeration bar. I swept the pool with only the normal returns running, and it took quite a bit longer for the dirt not captured by the filter to settle out again.

This evening, after two days of dogs in the pool, I again had a build-up of dirt on the bottom. Testing showed my pH at 7.2, so I set up for aeration again, as I like it to be around 7.5. Swept the pool, and within half an hour, most of the dirt had settled back on the bottom.

I do need to clean the filters, and try this again with the aeration bar installed.