Shock or Drain?

Good morning to all -- This long-time pool owner but new forum member has a dilemma. We are relandscaping in our backyard, including the asphalt and pool coping. This has necessitated the covering of our pool and prohibition of maintenance for a period of two weeks. Worse, now we have to lower the level of the pool below the skimmer line, so I will have to turn the filtration off entirely for about a week.

Bottom line: our pool is surely a filthy cesspool and will probably get worse before I can make it better.

At a minimum, I will need to shock the heck out of it, and should that be my best course of action, I would be grateful for advice about how to perform an extreme shock. But I wonder if maybe I should just drain the thing, scrub down the walls, and start over.

Any and all thoughts and comments welcome.

Rick A.
Pleasanton CA

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Rick, here at TFP we use a process called "SLAM" - the link is below in my signature. It can work on pools that have sat for a whole season or more. Now being in CA, if your current water CYA (stabilizer) and/or hardness (CH) is already high, exchanging some water now may be beneficial. But to drain the entire pool, especially just for algae, is not something we normally recommend unless you know the pool shell will remain stable (water table beneath), you have a specific purpose (i.e. acid wash, replaster, repairs, etc) and/or do not leave the plaster exposed too long. If you have any questions about the SLAM process, please checkout that link below for more info. Hope that helps.


Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
Bedford, TX

It looks like you have been a member here since 2016... If this is true, you probably know that we like to make decisions based upon test results... For example; if your CYA was 180, it would certainly make sense to drain and start over.. Do you know what the test results were before you covered your pool?

How are you currently chlorinating your pool?

Not too long ago, it was almost "illegal" to drain and fill a pool in CA.. :p Is that still the case in your area?? The cost for water would certainly play into any draining decision..

Thanks for posting,

Jim R.
Thanks, Splash --

I am gratified to know that I am not too far gone (watched the green pool video; okay, my problems are minimal...). One follow-up question: vacuuming prior to the process will be key, I know, with all of the debris created by the jackhammering. The green-pool video mentioned vacuuming to the yard instead of through the filter, but I don't know how to do that. Our vacuum is designed to work with the filter and skimmer; is there a way to retrofit it so that I can suck debris out of the pool entirely?

- - - Updated - - -

Thanks, Jim. Draining and filling our pool wouldn't be cheap, but as part of a $45K remodel, I could justify it if it were warranted. I am concluding from the comments here, however, that it is not: that I can shock and treat the pool. See my query to Texas Splash about vacuuming to the yard instead of through the filter -- that is my current quandary...

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Rick, it really depends on your filter type. Some folks will "vacuum to waste" in such situations. They have either a sand or DE filter which may have a multiport valve that can be moved to waste so when they backwash, the water goes straight to the yard/drainage area without going into the filter. If your filter does not have a multiport valve (i.e. cartridge filter or DE filter with a plunger valve), then you probably can't take advantage of that backwash to waste process. That's how my pool is. I vacuum from the poolside skimmer into my cartridge filter and that's it. If that's the case with you, then some folks might rent a sump pump suitable for pulling water and debris to waste. They'll sweep and try to remove what they can manually, then let the sump pump do the vacuuming for them without using the pool filter. Make sense?
When I vacuum, I place the hose into one of two holes in my skimmer and everything gets sucked into there. I have not paid attention to what the other hole is for; might that be part of the "multiport valve" that you refer to?

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
No, the poolside skimmer hole(s) only bring water back to the pump and filter. The multiport is just in front of the filter itself back at the pad (see below). I suspect you have a cartridge filter like me, but you can confirm when you get a chance and update all your equipment in your signature. There's no missing a multiport valve when you have one. :)



Bronze Supporter
May 11, 2017
Twin Cities, MN
Do you have a 3 way valve like this one between your pump and filter? This one is set to send water through the filter. If I rotate the handle 180° it will send it out to my yard.

3 way valve.jpg
Do you have a 3 way valve like this one between your pump and filter? This one is set to send water through the filter. If I rotate the handle 180° it will send it out to my yard.

View attachment 73948

I do have a valve that looks like that one -- our system operates it automatically when the solar heat is enabled or disabled, so I'm not sure that it performs the same function as yours. At a minimum, I would need to connect a hose to it or something because I am certain that I don't have anything that automatically sends water to the yard. But if the plumbing is in place for that, and all I have to do is connect a hose and run it out to the yard, that would be great.