Why Drain Pool with High CYA?

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Guessing you're estimating trips to the bleach store... my fogged-up crystal ball says you'll find 10% or 12.5% and you'll go through around 2 gallons a week during summer, and less than that per month around Christmas.
 
Thanks again everyone!

Does anyone have any tips for draining and refilling a plaster pool in southern Arizona this time of year? I'll probably do the drain and refill in mid March. I'm may do a partial drain, or I may do a full (80%) drain; I haven't decided yet. I'm a little worried about floating the pool, but I'm more concerned with the plaster drying and cracking (I've read that this can be a problem). Since I'm filling with water from the house, there's only so much flow rate I can achieve, and I'm concerned about the plaster. If I use the giant-tarp method, the plaster could still dry out, but it will be hidden from the sun. Would this be acceptable? How many days can the plaster remain dry before a problem develops? Would a better bet to be to drain from the deep end and refill at the shallow end, matching flow rates between the drain and fill? That way at least the plaster would never be exposed.

Thanks again!
Bryce
 
With your solids content the water exchange process should be quite doable. You would need a small sump pump, place in the deep end and measure how much output it has, then match the same gpm out with fresh water in with the hose in a skimmer or other that will reduce mixing. Your pool is not huge. At 7 gpm it will take about 1400 minutes, or right at a full day.

I would not suggest the tarp method. Not really necessary in your situation.
I also would not be real concerned with floating your pool in Tucson. But that is always a risk.

Take care.
 
Do you use Tucson Water??

If so, DO NOT DRAIN YOUR POOL (now). Tucson water bills a flat rate for sewerage fee based on your average water usage for the months of Jan/Feb/Mar. if you drain and refill before your April meter reading, you’ll spike your baseline water usage and then pay MORE money than you have to each month of the next year.

If you’re on your own well, do as you wish.
 
CYA and calcium are solids in your water. Also salt from past chlorine or acid additions. Those salts make your pool water more dense than the fresh water. Thus your fresh water will tend to 'float' on top of your existing pool water.

Heed Matts' note on when you should do your water exchange cost effectiveness. But be sure to maintain your FC as high as possible until you exchange.
 
PoolBryce said:
Hey Matt,
I am on Tucson water. Thanks for the reminder about this. I will call them and see if I can have 10k gallons waived from my meter reading. Otherwise I guess I'll wait for Apr 1.

Cheers,
Bryce
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They might do that but they usually only waive sewerage fees for a pool fill. You could do the refill and then try to claim a high water usage accident but they typically only do a high water usage rebate once every 3 years. So, if you use that wild card now, you won’t get to use it again for three years. Last year I had a major water leak in July that caused my water bill to read nearly 40CCF. I showed them that my historical usage was typically half that volume and they credited me back the difference. Can’t do that again until 2020.

They’ll likely tell you to wait. Honestly, I would wait rather than trying to fight to get money back.
 
Hey Matt,
Yeah what I meant was having the 10k gallon size deducted from the sewer bill only. Where I live, that’s calculated from the water usage (I don’t think sewer is actually measured). They just calculate it based on water usage. I do intend to pay for the water to fill the pool, but I hope they can waive that amount from the reading for the purposes of calculating the sewage amount.

Bryce
 
The new water is less dense than your pool water, so it floats on top and pushes the salty, colder water down.

The ticket is to keep the water still. Be sure to shut off anything that could mix water. A random start of the pool pump in the middle of it would wreck it, or anything like a water feature, spa, etc. No brushing, no swimming, pool pump off, yada, yada. If it was real windy, you could put the cover on it if you had one, or wait for an average day.

If you can't match flow, just let it fill up high, then shut off your fill line for a bit, or vice versa. Measure the flow rate (how long to fill a 2-gallon pail) of your fill line and track the time in minutes X gallons per minute, and let it run the amount of time that equals the gallons you want to get rid of.

A call to your water supplier might be worthwhile. Rule out the chance that they're using your consumption to determine your sewer rate for the upcoming year. If need be, do it after the period they use for sewerage estimate. Ask if any fees or higher incremental rates are avoidable for a pool refill.

- - - Updated - - -

Whoops, should have checked, others had you covered.
 

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PoolBryce said:
Hey Matt,
Yeah what I meant was having the 10k gallon size deducted from the sewer bill only. Where I live, that’s calculated from the water usage (I don’t think sewer is actually measured). They just calculate it based on water usage. I do intend to pay for the water to fill the pool, but I hope they can waive that amount from the reading for the purposes of calculating the sewage amount.

Bryce
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I’d be interested in hearing what they say. I too will be draining 16k gallons this spring for CH reasons. But my plan was to wait until after my April reading.
 
If the pool warms up too much, there's a point where it won't work. For example, if the pool is 4000 ppm salinity and 85F, and the fill water is 400 ppm and 65F, both fill water and pool water will be the same density, and the water will mix.
 
My fill water with will have a TDS ~ 500ppm or so with a chloride content around 150ppm or so. The water out of the tap is about 78-80F. Pool water will be 4000ppm NaCl, 1400ppm CH and probably about mid 70’s in April.

Thoughts?
 
With temperatures that close, it will easily work. Your city mains water is warm in April! The CH is working in your favor as far as maintaining separation. I tink.

I'm also really, really hoping you'll help me get either TDS or salinity on both sides of the equation. I chose salinity only because it's more commonly talked about in TFPC, so would help contribute to the simple mandate. Ocean scientists (where all those beautiful calculations come from) seem to use TDS and salinity interchangeably, which doesn't seem right to me, but might be good enough. Maybe they do so because of the very high salt levels. If there's a way to make the calculator better by inputting CH (or other numbers) that would be great, as long as it stays TFPC simple and effective :)
 
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JoyfulNoise said:
Next time you happen to be near their pool, grab a water sample and see what it looks like....you might never let your kids swim there again ;)

Her approach to pool care is pretty standard - throw in whatever the pool store tells you too and hope for the best. Given that you're on LI (from where my peoples come...), you get enough annual rain dilution and snow melt to make most CYA problems manageable. As long as the pool is getting enough fresh water exchange each year, I bet her CYA levels are fairly low to start with and then climb throughout the summer only to have them go back down when the pool is drained for winterization and then refilled over the winter. Pucks can work in a climate like that as long as one is careful to consistently push up their FC as the CYA increases. The occasional shock is probably just enough to keep anything really bad from happening especially if cal-hypo is used instead of dichlor.
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I'll vouch for that. When I had an above ground pool the weight of the snow on the cover would push the water down causing it to rise against the wall and out the skimmer. Once the snow was melted (water) I'd pump it off or back into the pool to replenish lost water.
 
Hi again everyone,
This weekend I did a drain and refill concurrently using the methods outlined above. I was targeting a roughly 80% water change, but I think I may have done more than that. I just spent an hour with my K-2006 test kit and got the following numbers:

FC = 0.6 ppm
CC = 0.0 ppm
pH = 7.8
CYA = [sample was so clear that I couldn't measure it. The lowest my kit goes is 30, and I could easily see the dot at that level. The sample was slightly opaque, so there is some CYA in there; maybe 5-10 ppm if I had to guess]
CH = 170 ppm
TA = 125 ppm

So obviously I need to increase my CYA (guess I drained way too much) and my FC. I've never bought CYA before. Does anyone have any suggestions on type and brand? I can take care of FC my self (using liquid chlorine).

What do you guys think of my TA level; it's certainly at the top of the recommended range. Would anyone suggest that I do anything to bring TA down? If so, how would I do that? I have 1.5 gal muriatic acid. Is that used to bring down TA, or does that only bring down pH? My Taylor test kit says to get TA where I want it before attempting to tackle pH.

My CH is 170. The Taylor test kit says this is good, but PoolMath says I actually need to be 250-350. Is PoolMath correct here for my plaster pool?

One last question: since my CYA changed so much (>300 before water change, <30 now), I'm somewhat inclined to have the pool store double check my numbers. Is there any need for that? This is only my second time using my K-2006 test kit, so I don't really trust myself with it yet. I did run some of the experiments twice (CYA, TA, pH, and FC) and got the same numbers each time, so that's a vote of confidence, I suppose.

Thanks again for all the help!
Bryce
 
I'd start with 40 CYA and see if that holds your FC. If not, raise it by another 10 and see if that does the trick. Better to go up slowly rather than all at once 'cause you know how hard it is to remove....

Maddie :flower:
 
Please trust YOUR testing. The CYA test is the one the pool stores get wrong more often. Do like Maddie says...shoot for 40 and see how it goes.

Act as if you have 10 for buying and adding more CYA. I get mine from Walmart or Lowes. Brand really does not matter so long as it is 99% cya. To add it to your pool do NOT follow the directions on the bottle! Put it in a sock(s). Tie it off and hang it (use a broom stick or such with something heavy on it) right in front of your return. You can squeeze the sock to help it dissolve a little faster. Once it is all dissolved wait a day before you test.

When you do the CYA test you need to GLANCE for the dot. Do NOT look for it. Just GLANCE in. What I do is start at the first line (100) and go line by line until I cannot see the dot with a GLANCE.

We will work on your TA once everything else gets balanced. Remind me and I will walk you through how to do it. TA is the last thing we work on.

I THINK I hit everything.If I forgot something let me know. :hug:

Kim:kim:
 

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