Getting ready to drain. Anything I should know first?

Just started with our pool (bought 20yr old home last November with a pool of unknown age) and planning on using TFP to keep it clean rather than the pool store nonsense.

I got my new TF-100 test kit in yesterday and immediately followed the directions for doing a CYA test, as that's the number I'm most concerned about. As I feared, I'm looking at right around the 200ppm mark. (1/2 diluted, dot disappears around 100, maybe just a hair more).

I have a submersible pump and some hose on order, and a plan for draining. If my testing is right I'll need to drain somewhere around 80% to get to what I want. How will I know when I've drained enough? Also, it's a plaster pool, so are there any pitfalls I should be aware of. The water table is pretty far down here in the desert, so I'm not worried about the pool floating, but I am concerned with cracking or buckling of other kinds. Should I be? I don't know how old the pool is, but it's in very good shape.

Seems pretty inefficient to me to drain, fill, drain, fill, drain, fill to get to the number I want, so I'd rather just do it in one shot if I can.



Well-known member
Dec 23, 2012
Manassas Park, VA
I can't provide much input in regards to your questions but if you move forward with your plan I recommend calling your water company and see if they can waive the sewer fees for filling up a pool. My local water company will not charge sewer fees for filling a pool.


TFP Expert
Platinum Supporter
May 23, 2015
Tucson, AZ
In the dry desert climates like what we have, you want to drain the pool as fast as you can (preferably overnight) and then start filling it up right away. Plaster should not be allowed to dry out for too long or else it can crack. You also want to make sure your weather is cool when you do it (preferably air temps lower than 85F) so that the plaster does not heat up too much. Remember, the plaster is used to being submerged in water so it is constantly being compressed by the weight of the water against the gunite shell and it's temperature variations are very slow. Exposing the surface to air relieves a lot of that stress and allows the surface to heat and cool much more rapidly.


Mod Squad
LifeTime Supporter
Jan 17, 2012
Evans, Georgia
There are a few folks who have had concerns about emptying their pool yet they needed to drain water. The trick some folks have used is laying a huge tarp over the pool and you drain from below the tarp while at the same time you are refilling above the tarp. It has to be a big tarp mind you, to absorb the weight and pull-down of the new water. When done you just pull the tarp out. SO that's one option.

You could do multiple smaller drains. It uses more water but more water is staying in the pool during the procedure too.

Drain at night and refill real fast? Perhaps drain at night and have a water truck deliver early the next day?

Just some ideas..... you're in such a hot environment I don't know any other tricks to offer. :/

Yippee :flower:
Thanks for the insight. Luckily, the temperature here for the next week is supposed to be very mild. The highest daytime temp I'm looking at for next week is around 85 with overnight lows in the 40's and 50's. The days I'm actually planning on doing it are forecast to be a high of 75. If my target to stay under is 85 then I shouldn't have any problem.

The tarp idea is a neat one, but tarps and I don't tend to get along very well. :)


TFP Expert
Platinum Supporter
May 23, 2015
Tucson, AZ
To drain fast, rent two submersible pumps instead of one. Get the largest flow rate ones you can find. If you want to keep the plaster wet while it's draining, you can periodically hose it down with your garden hose. Keeping the plaster moist will do a lot to protect it while you drain. Draining is also a good time to get in the pool and do any tile cleaning work.

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