Been reading a lot of threads about people who buy a house with a pool that "hadn't been touched in years". The pools are predictably mucky, green, disgusting, etc. People go on to SLAM their pools, and it takes usually a couple of weeks and everything is perfect. However, I had a dumb question. When faced with such a gross looking pool, why don't people simply drain/refill? Why go through all the work & hassle of buying/transporting dozens of gallons of bleach, sweeping/vacuuming multiple times a day, raking stuff out of the pool with a skimmer, etc? Is it about saving cost of the fill water and chemicals to re-balance, or is there another reason?
dumb SLAM question on really green/gross pools
- Thread starter demento
- Start date
A few possible reasons to SLAM and not drain/fill:
1. Cost savings
a. If water is expensive
b. Having to re-balance (add CYA, salt, etc)
c. Algae still lurks and may still need to SLAM anyway
2. Ecological concerns
a. Drought conditions, save the water
b. No where to safely pump 1000s of gallons of water
c. No access to adequate refill water (private well, high metal content, etc)
3. Damage to pool:
a. In hot climates, you do not want the plaster to be exposed to high heat and intense sun for very long
b. In high water table areas, if you drain too much, the pool can float out of the ground
c. If an older vinyl liner, you can not drain it or the liner may shrink and rip when you try to refill.
1. Cost savings
a. If water is expensive
b. Having to re-balance (add CYA, salt, etc)
c. Algae still lurks and may still need to SLAM anyway
2. Ecological concerns
a. Drought conditions, save the water
b. No where to safely pump 1000s of gallons of water
c. No access to adequate refill water (private well, high metal content, etc)
3. Damage to pool:
a. In hot climates, you do not want the plaster to be exposed to high heat and intense sun for very long
b. In high water table areas, if you drain too much, the pool can float out of the ground
c. If an older vinyl liner, you can not drain it or the liner may shrink and rip when you try to refill.
Good answer, thanks! I think that there'd be no way my wife would allow me to try to clean something like that up. We got a tiny amount of dirt in our new pool from the landscapers installing our grass/plants, and she wanted to drain/refill just because of that! 
In addition to Jason's great answer you have the issue with algae itself. Just draining and refilling will not get rid of it. It will be in every nook and cranny of the pool just waiting for you to put nice clean water in so it can start growing again. Some folks have shown up,here after a full drain/refill and they still needed to SLAM because the algae came right back.
It's not a dumb question at all. Jason covered most of the why-nots, but I think he should have included "Don't want to run the well dry" as a reason not to.
Believe it or not, once in a while conditions are right and time is tight or it's such a mess that there could be a car submerged under the scum and we do recommend a complete drain. It's more common that we recommend a partial drain due to astronomical CH or CYA values. In those cases, a vacuum to waste or a rented trash pump gets the worst of the sludge out of the water before the expensive bleach gets wasted trying to oxidize the organic debris.
I know if I moved into a house with a mystery murky green chemical nightmare swamp I'd drain in a heartbeat. The expense of startup chemicals won't be greater than the cost of all the DE and bleach used up in a SLAM. But a good many people just have algae from poor closing at the end of the season. It bleaches out to grey in a day or two and the bleach consumption drops off quite a bit after that and it's mostly just waiting for it all to filter out. In the end, the time and expense are probably about the same in a case like that.
Believe it or not, once in a while conditions are right and time is tight or it's such a mess that there could be a car submerged under the scum and we do recommend a complete drain. It's more common that we recommend a partial drain due to astronomical CH or CYA values. In those cases, a vacuum to waste or a rented trash pump gets the worst of the sludge out of the water before the expensive bleach gets wasted trying to oxidize the organic debris.
I know if I moved into a house with a mystery murky green chemical nightmare swamp I'd drain in a heartbeat. The expense of startup chemicals won't be greater than the cost of all the DE and bleach used up in a SLAM. But a good many people just have algae from poor closing at the end of the season. It bleaches out to grey in a day or two and the bleach consumption drops off quite a bit after that and it's mostly just waiting for it all to filter out. In the end, the time and expense are probably about the same in a case like that.
