How to figure out whether/how to do a water exchange?

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A

Abnaxis

Well-known member
Jun 28, 2021
95
Indiana
Pool Size
6500
Surface
Fiberglass
Chlorine
Salt Water Generator
I am taking over a pool on a new house that I just bought. Still waiting for my test kit to see just what the water looks like from the items I can test, but regardless of what I get from the test I've been mulling over doing a water exchange just so I can start with a clean-ish slate.

My pool has a single skimmer and a floor drain to go to the pump supply, and my filter valve has a waste position piped to the sewer, so I'm thinking I can just put a plug in the skimmer, put a hose in the top of the pool and run the pump for a day or two to exchange the water, with clean water flowing into the top and dirty water going through the pump to the sewer. There are a few things I wanted to run by people with more expertise/experience than me first though.

First, is this a good idea, or am I just being paranoid? The previous owners were not conscientious homeowners and the people I'm 90% sure were responsible for the pool before the previous owners abandoned it are...not people I trust (only pool company in town :mad:)

Second, the pool is quite green and needs a SLAM, so what should my order-of-operations be? I obviously need to get in there and vacuum out the leaves in the bottom before I use the main drain for a water exchange, but I don't see any way algae would stop the water flowing, and it seems like extra effort to balance the chemistry twice. Although, if I SLAM first it might make the "getting all the dead junk making the water cloudy out of the pool" stage of a SLAM quicker since I'm pumping water out of the waste bypass instead of waiting for the filter to handle it? Maybe bring FC to SLAM levels, wait for the green to die/OCLT to come back good, and start draining?

Third, it's easy enough to figure out the flow rate of my garden hose with a bucket and a stopwatch, but how do I figure it out for my pump? I have no idea how much water is moving into the drain (or the return jets when it's in filter mode, for that matter).

EDIT: Fourth, are skimmer plugs designed for use while the pump is running? They're intended for winteriziation, I don't think they're meant to hold pressure? What about the supply pipe itself? I'm not going to break somthing doing this, am I?
 
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Figure out pool volume, then simply add 5ppm of liquid chlorine (using pool math) until your test kit arrives. No point in SLAM until you can accurately measure...
Wait until you test the pool to see how bad off you are - if CYA or CH not out of control, then there's no reason for replacing.

Your plan to pump out and replace is nothing I've ever tried - I went the traditional route pumped down, then refilled without issue.
 
reggiehammond said:
Figure out pool volume, then simply add 5ppm of liquid chlorine (using pool math) until your test kit arrives. No point in SLAM until you can accurately measure...
Wait until you test the pool to see how bad off you are - if CYA or CH not out of control, then there's no reason for replacing.

Your plan to pump out and replace is nothing I've ever tried - I went the traditional route pumped down, then refilled without issue.
Click to expand...

Erm, this is one of those things where it was clear in my head, but not in my message. Yes, I am definitely waiting for the test kit before I do ANY of the above.

My apprehension toward "not doing anything unless the test says CH or CYA is off" is that the test kit doesn't test everything. I have no idea what's been put into the water which the test DOESN'T test for. For example, I heard the "pool guys" talk about dumping a bottle of (probably copper) algaecide in there.
 
Abnaxis said:
Erm, this is one of those things where it was clear in my head, but not in my message. Yes, I am definitely waiting for the test kit before I do ANY of the above.

My apprehension toward "not doing anything unless the test says CH or CYA is off" is that the test kit doesn't test everything. I have no idea what's been put into the water which the test DOESN'T test for. For example, I heard the "pool guys" talk about dumping a bottle of (probably copper) algaecide in there.
Click to expand...
Hear you loud and clear - post a set of full results, then the experts here can advise.
 
Just got my first results:

------------------------------------------
Test Results 07-31-2021 @ 03:31 PM
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Free Chlorine: <0.5
pH: 7.8
Total Alkalinity: 260
Calcium Hardness: 1000
CYA: 0

Now to go look at pool school to figure out what to do about this...
 
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With a CH that high, you’ll need to drain before worrying about much else. No CYA is the reason for no FC. Both are critical components for sanitation. But rather than dump a bunch of chlorine, I’d reduce water levels 65%, then fill and get after it in regards to balance.
 
I'll check the spigot by the pool here in the next couple hours.

One thing I wanted to ask: It's the CH test that turns pink to blue right (I'm out getting food right now)? That one was purple for a while before it turned full blue, no matter how much I mixed it. It's got to be full blue to take the reading, right?

Only makes like a 100 ppm difference so not a big deal; but I'm still curious
 

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I can't actually get the CH test to work without fading on my source water or my pool water. I tried adding 5 drops of R-0012 at the start of the test, per the advanced instructions, but it made no difference and I don't have distilled water here to dilute the samples. Both spigot and pool start purpling at about 900ppm and turn full blue at about 1000ppm.

TA for the spigot reads 210ppm. I didn't notice when I ran the test on the pool that you're supposed to wipe the tip of the reagent between drops, but I did wipe for the spigot test
 
Then you have really high CH fill water.

You get a lot of rain so you should be able to manage that by draining and filling. Easiest would be to drain about half the pool volume and use softened water to fill it up. But that may not be all that easy.
 

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