First Test -- preparing for drain and refill

apv

Active member
Apr 30, 2019
38
Austin, TX
Got my first water test back by taking a sample to local pool store (I am waiting on my test kit to arrive).

FC: 0.12
TC: 0.32
Combined: 0.2
pH: 7.8
Total Alk: 98
Adjusted Alk: 57
Calcium hardness: 583
CYA: 122
Copper: 0
Iron: 0
TDS: 0
Phosphates: 522
Saturation Index: 1.0

Questions:

1) What's a reasonable way to estimate pool volume? The most simplistic method I could come up with assumes the pool is two rectangles (one shallow and one deep). Is this how other folks do it? This test assumes that my pool is 17,000 gallons.

2) If I drain and refill b/c of my CYA issue -- should I do it simultaneously ie hose in the shallow end, sump pump in the deep end? Or should I just drain first and fill after? If possible, should I use my pool pump to pump out the water or rent sump pump?

3) Is Calcium Hardness an issue? If so, suggestions?

4) WRT pH, I just planned to add a bit of muriatic acid. Thoughts?

Any and all suggestions appreciated. TIA.
 

Mendy48

Bronze Supporter
Apr 27, 2018
653
Midland, MI
Welcome!!!

Awesome that you got your own test kit.

There's this link that gives you an estimate of what your pool volume is. Scroll all the way to the bottom ..under...Estimating Pool Volume.

I'll wait to get your own test kit to get the actual value of your CYA, but assuming it's 110, you have to get fresh water to lower your CYA. You can exchange some water without draining. Use a low-speed sump pump in the deep end and pull water from there, while at the same time, add water in the shallow end. To do it this way, note that the water you are filling at the shallow end should be the same temperature or warmer than your pool water. If your fill water is much cooler than your pool water, then switch it. Add the water to the deep end (hose at the bottom), and using a sump pump pull water from the shallow end (top).

I'll let an expert chime in here shortly about your CA. It seems a bit high. I've read that CH will not come out of your pool unless you drain, but I'll let an expert chime in here shortly.

Again, I'll wait for your own test kit to test your pH. If, in fact, it is 7.8, then yes..you'll use muriatic acid to lower it using the correct calculation in PoolMath

Experts will chime in here shortly....
 
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Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
22,059
San Dimas, CA (LA County)
Got my first water test back by taking a sample to local pool store (I am waiting on my test kit to arrive).

FC: 0.12
TC: 0.32
Combined: 0.2
pH: 7.8
Total Alk: 98
Adjusted Alk: 57
Calcium hardness: 583
CYA: 122
Copper: 0
Iron: 0
TDS: 0
Phosphates: 522
Saturation Index: 1.0

Questions:

1) What's a reasonable way to estimate pool volume? The most simplistic method I could come up with assumes the pool is two rectangles (one shallow and one deep). Is this how other folks do it? This test assumes that my pool is 17,000 gallons.

2) If I drain and refill b/c of my CYA issue -- should I do it simultaneously ie hose in the shallow end, sump pump in the deep end? Or should I just drain first and fill after? If possible, should I use my pool pump to pump out the water or rent sump pump?

3) Is Calcium Hardness an issue? If so, suggestions?

4) WRT pH, I just planned to add a bit of muriatic acid. Thoughts?

Any and all suggestions appreciated. TIA.
I wouldn't do anything based on pool store testing. They are wrong so often, amnd CYA testing most of all. If you assume 122 is correct and then drain half and refill, what are you going to do when it reads 100 still? And that is not so far out. When I took over my pool, I had to dilute things a lot and came up with 220-240 on the CYA .And it was clear! That's what a diet of pucks can do.

If the CH is that high, it's still manageable, but lower is better.

For volume, split it up into multiple sections. You'll be fine-tuning that over time as you see what various chemical additions do. Right now you just need to be within a couple thousand gallons. When adding chemicals, go low. You can always add more, but you see for yourself what you need to do if you go over.

After you've drained and refilled, you'll need to give the water a couple hours of pump time to mix things, and then run a whole new set of tests. And if the pH needs lowering then, yes, Muriatic Acid is the preferred way.
 
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apv

Active member
Apr 30, 2019
38
Austin, TX
So, I drained (1/2 way) and refilled my pool. Draining was relatively easy and fast (6 hours or so) with pool pump on waste setting. My garden hose clearly doesn't provide the same GPM. Took 24 hours of constant running to get back.

I re-tested (with the recommended test kit) and CYA is around 90. Down from 122 (from pool company test).

My plan:

The next few days in Austin, TX will be rainy so I plan another drain and refill.

Q1: Should I drain and refill completely or another partial? My worry is that between the rain, the hot Texas sun could peek out and scorch my plaster. (And I assume it would take about 48 hours of running the hose to fill back up).

Q2: The pool is pretty gross now as I haven't added chemicals. The pool service guy recommended PoolRx (copper thingy) but based on what I have read -- that is not a good long-term idea. I don't plan to add chemicals since it wouldn't make sense pre-drain. Am I missing anything?

Q3: Once the pool is filled back up, I plan to SLAM -- anything else I am missing?

Q4: What tends to be cheaper: delivered pool water or city water (garden hose)?

Thanks in advance
 
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duraleigh

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Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
32,351
Sebring, Florida
Welcome to the forum:wave:

Post the rest of your test results.

Stay out of the pool store. It will only get you confused
 

duraleigh

Admin
Mod Squad
TFP Expert
Platinum Supporter
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In The Industry
Apr 1, 2007
32,351
Sebring, Florida
Q1 - Drain your pool at the same rate you refill and do so simultaneously. Several threads on the forum as to how. Pool level never lowers so your plaster stays protected

Q2 - You are on the money.....no need to add when you intend to drain it away. Stay away from copper (and maybe that pool guy, too:oops:)

Q3 - No, I agree with your plan. Make sure you understand the SLAM before you start.

Q4 - city water by far.

I would suggest a 50% drain and refill. That will land your CH at an almost perfect of 275 and your CYA around 40.....both very good numbers.

Prior to your SLAM, drop your pH down around 7.2 with muriatic. Don't wait too long on the drain/refill......the algae will only get worse.