Firstly... We've long been BBB believers and have used this forum and "pool school" extensively and successfully. We're in year two of loving pool ownership, and our own water tests, and the tests at the local pool store, always show good levels across the board due to your great information. So, THANKS!
Secondly... We never felt the need to post all this time because so much great info is readily available. But, today is the day.
We're unsure if we have the beginnings of an algae concern. After a period (say, overnight) of non-use, we find sediment on the floor of our pool. It is almost like "ash" from a fireplace in that it is extremely fine and disappears when touched. No grit like sand or dirt would have.
Here are our pool specs:
- 15 x 30 above ground
- 10,000 gallons
- sand filter runs 5 hours per day on a timer
- solar cover at night
- the pool receives full sun 100% of every day
- some blow in from trees at the edge of the property but not a major source of litter
- no nearby activity (e.g. construction or similar) that would cause a lot of dust
Here's our regimen:
- We check all levels daily
- We never see wide swings in the numbers
- Most of the time we only need to add some liquid chlorine, sometimes some muriatic acid
- We vacuum about twice a week
- Rigorous swimming for multiple hours per day (we're "that house" where all the kids come to play and hang out)
Here's our levels today (which are very similar to what they are every day):
- PH = 7.6
- CYA = 40
- FC = 5
- CC = 0
Water is crystal clear, the walls are clean too.
Steps taken so far.
- We backwashed last week.
- We cleaned the solar cover to ensure we're not dropping in sediment of any type every night.
- We bought a brush and scrubbed all the walls and seams (despite no visible evidence of any issue)
- We pulled the ladder out and found a bunch of hidden grime on the back side. We cleaned aggressively with bleach and a brush. Rinsed, replaced.
- We carefully vacuumed, flushing to waste rather than filter.
- Rechecked all levels after topping the pool off with hose water. Needed a little chlorine to get back to the numbers shown above.
Two hours later, with the filter still running, we had sediment at the bottom again. Same type of ashy stuff that disappears when you try to touch it.
What do you think we have settling on the bottom of our pool?
What steps can we take to eliminate? Shall we just increase our filter time and continue with the new addition of manually brushing?
Should we "shock"?
Is it really nothing to worry about since our numbers are continually good?
Thanks in advance!
Bob and Meg