Grit on walls & floor

[kfpool]

I recently purchased a home with a pool that had cloudy water. The previous owner was elderly and pretty much just fed the pool steady diet of chlorine tabs and did little else to the pool. Initial Testing revealed very high CYA. I posted the results here and received some advice on the next steps. I drained approx 75% of the water to bring the CYA to accceptable levels. As the pool was draining I noticed a grit in the steps / walls / floor & began brushing & hosing off the walls as the level dropped. I ran the filter continuously during the draining process keeping a close eye on the filter pressure and cleaning as required (Every 1-2 hours) The filter was always clogged with a green-yellow film and the gritty substance. I suspect that this is calcium but have not had a chance to get out to get some muriatic acid to test it. I have also noticed that the grout in the tiles at the water line seems to be thinning and a couple of tiles had fallen out.

I have included a photo of some of the grit I collected from the bottom of the pool along with a photo of the pool wall & tile

What are my next steps?
Continue brushing & hosing while running the filter until most of the grit is gone?
Refill and Slam?
More agressive cleaning methods?

I really want to get water back into this thing as soon as possible, A little nervous about the 75% drain.

Results of the last test the day before I started draining. I used the modified test to measure for the higher CYA levels

FC 8
CC 2
TA 150
CYA 190
PH 7.3
CH 425

 

[Divin Dave]

Hi,
It might be calcium, but as you mentioned you'd have to test to confirm.

The plaster in the pool looks good. Just fill it back up and balance it to TFP recommendations. If your FC tests say you need to slam, then do it. If the FC is good, CCs are good and OCLT is good, then there is no need to slam.

So the million $ questions is... why the grainy stuff? Hard to say since there is no historical record of the pool chemistry or maintenance regimen. But likely, the CH and Ph weren't balanced properly and this was the result. At least thats my best guess.

Im 100% positive though, that going forward with proper water balance, you will never see this again.

 

[kfpool]

I have been running the filter this morning & brushing the pool toward the floor drain. Filter is plugging every 15 min or so. Should I continue with this for a while before I fill? Does't seem like I would want to leave known debris in there.


Sent from my iPhone using Tapatalk

 

[Divin Dave]

If I were you, I would continue to refill and sweep while it's filling.

Im not surprised your filter fills quickly, thats only a 120 sq ft filter which is not very big.

I have a question. I think the answer is no, but just want to confirm.
When you drained the pool, did you do a wash the plaster with muriatic acid? If so, then thats why you are getting the grit.

 

[kfpool]

Nope, didn't wash with acid. I just noticed when I ran my hand along the wall that it felt gritty.


Sent from my iPhone using Tapatalk

 

[kfpool]

Once I knew the got was there I got busy trying to get it out


Sent from my iPhone using Tapatalk

 

[Divin Dave]

Good deal.
It lools like your plaster is some sort of the more high class variety. Maybe quartz or mini pebble or something like that. If it is...
The quality of the plaster itself is what keeps the aggregate within the pool finish. Im suspecting that the water balance was poorly maintained with a low Calcite Saturation Index which can over a period of time start to dissolve the plaster. If that is the case, it will explain the gritty feel and the aggragate fall off.

Dont worry too much about the ongoing effects, the plaster is more than thick enough to still be ok. You just need to properly maintain the water balance so it doesnt happen again.

Nope, didn't wash with acid. I just noticed when I ran my hand along the wall that it felt gritty.


Sent from my iPhone using Tapatalk

 

[kfpool]

Finally got some muriatic acid. When applied to the granules, it does not react or foam. I am guessing I should just start filling and keep the filter running as long as I am here to monitor the pressures?


Sent from my iPhone using Tapatalk

 

[Divin Dave]

Thats what I would do.

Finally got some muriatic acid. When applied to the granules, it does not react or foam. I am guessing I should just start filling and keep the filter running as long as I am here to monitor the pressures?


Sent from my iPhone using Tapatalk