High CYA, questions about safest way to drain

[colini]

Hello All,

I've recently become the owner of a pool and I'm learning how to take care of it. With some help from other forum readers, I've determined that the CYA level is around 200 and I plan to drain a lot of water to get this down to 50 - 60. (In central Texas with a lot of sun in summer, maybe 60 is ok?)

First question is, how much can I safely drain before filling it back up? To go from CYA 200 to 50 I'd have to replace 75% of the water! Can I do that at once or is it better to do it in stages?

Second, can I drain it with my pool pump? I have 2 skimmers and drains in the bottom of the pool. Is it possible to disable the skimmers and use the bottom drains to remove so much water? There is a multiport valve but I don't really know how to use it. Is it safer to just buy/rent a submersible pump and use that instead?

Last question, assuming I remove 50% or more of the water it will take a long time to fill it back up w/ a single hose. While it's that low I can't run the filter, and I'm concerned it might turn green. Can I just add some liquid chlorine as it fills (to keep algae at bay), then get everything properly balanced once it's full again?

Thank you,
Colin

 

[HermanTX]

Hi Colin
There are multiple ways to drain a pool.
Please read
Draining - Further Reading

You may find it quicker to buy or rent a submersible pump as it is not recommended to use your expensive pool pump (but you can if nothing else is an option). The drain/fill water exchange may be an option to just drain then refill.

Do you need to do the drain right now - it may be best to let it cool down some in Austin but it your decision.

I would error on the low side - drain more then you think you need to, but do not drain 100%. CYA is a funny issue and since you are going through the process you do not want to have to do it again.

Have you checked your water table, are there any concerns of that being high?

If you plan to drain and refill then you could possibly use a second hose from the front of your house if that is feasible to help speed the refill. It took me 44 hrs to fill my 15k pool with a single hose. Be sure that your valves are turned that you are not having suction from the skimmers - both in the draining and refilling process.
Yes - you can dump some LC in while filling.
You may want to test your fill water now so you can anticipate what the CH, pH and TA levels will be.
Hope this helps.

 

[mknauss]

Welcome to the forum!
Do you know what your water table level is in your area? Are you near a river, lake, etc that may imply you have shallow water?
I suspect in Austin those are not concerns, but good to check.
This time of year, without any shallow water issues, you can drain the pool and refill. It is wise to use a rental sump pump (Home Depot has them with the hoses) to drain it quickly and restart the fill process. You do need to check with your local municipality on where you are to drain it to.
During the refill process you can add a gallon of liquid chlorine if you like. Just be sure it is well mixed in. Most likely do not need it but that is up to you.
I suggest you read ABC's of Pool Water Chemistry.

Herman beat me to it! Good job ---

 

[HermanTX]

One additional point - if you decide to use your pool pump to drain. On your multiport valve there is a notch for WASTE. That is where your would move the handle to have suction from your pool and discharge to your waste line. Is your waste line tied to your drainage system? Post some pictures of your equipment pad as that may help you identify the settings.
Also, you may also have a suction line for the skimmer and another for the main drain. You would turn the valve at that pipe junction to CLOSE for the skimmer. Again - post a picture if you need help to identify that.