What to do with these test results?

[NewWorldViking]

New to the forum and new to pool maintenance. I recently purchased a house with a 20+ year old in-ground pool so I'm now a pool maintainer. I'm also an engineer with google skillz so I've done research and not at square one. Still, I can use some advice on what to do in my particular situation.

K-2006 test kit results:

pH = 7.0
CH = 320
TA = 150
FC = 2.5 ppm
CC = < 0.5

And now the kicker...
CYA = Through the roof! Couldn't see the black dot after only filling up to the black background of the comparator tube which is completely off the chart. Re-performed the test with 50/50 pool/tap water. Couldn't see the black dot before I reached the 100 line. I guesstimate CYA is around 220-240 ppm.

I'm pretty sure this is from the previous owner using Trichloro pucks for years and not monitoring CYA (it's not the only thing he maintained poorly that needs TLC). I realize that this calls for the hard reset of drain/refill but I'm in Utah, a high altitude desert, and this is not the time of year to use that much water. That should be done during the spring snowmelt. Especially this year as we had below-average snowpack and didn't get the reservoirs completely full.

However, I see no signs of what I read results from high CYA. No cloudiness, water is clear to bottom. No algae. No smell. It looks perfectly OK. It's also only used by 2 clean adults, no children (and no chance of pee or feces incidents).

So two questions:
1) Could I have messed up the CYA test? (I did it 3 times following instructions. One all pool water, one 50/50 pool/tap, one all tap as a control. Both pool water resulted similar high CYA and tap control was zero)
2) Can this pool be made safe to use given the super high CYA levels until I can change the water next spring?

 

[Pool_Medic]

If you are hesitant to do a partial drain/refill, imo, you should use poly quat 60 weekly. Stop using pucks immediately and switch to liquid.

 

[cfherrman]

Raise you FC to 10 and drain/refill in the spring/fall, make sure it's safe to do so for your pool.

If it goes green on you drain and refill

 

[Texas Splash]

NWV, welcome to the forum! Sounds like you've done your due diligence with the CYA test, but just in case I'll pass along my go-to quote for how I do the CYA test in case anything seems different from what you did. I doubt it, but just in case....

CYA Testing:
Proper lighting is critical for the CYA test, so you want to test for CYA outside on a bright sunny day. Use the mixing bottle to gently mix the required amounts of pool water and R-0013 reagent, let sit for 30 seconds, then gently mix again. Recommend standing outside with your back to the sun and the view tube in the shade of your body at waist level. Then, begin squirting the mixed solution into the skinny tube. Watch the black dot until it completely disappears. Once it disappears, record the CYA reading. To help the eyes and prevent staring at the dot, some people find it better to pour & view in stages. Pour some solution into the viewing tube, look away, then look back again for the dot. Repeat as necessary until you feel the dot is gone. After the first CYA test, you can pour the mixed solution from the skinny view tube back to the mixing bottle, gently shake, and do the same test a second, third, or fourth time to instill consistency in your technique, become more comfortable with the testing, and validate your own CYA reading. Finally, if you still doubt your own reading, have a friend do the test with you and compare results.

If you simply can't change water and have to maintain a higher FC to compensate, which if it is closer to 200+ will be almost impossible, remember that your pH test will always show high with that elevated FC level over 10.

 

[setsailsoon]

Viking,

Welcome aboard! I'm a retired engineer and I was in similar situation 3 years ago when I took over the pool from the pool service. Since then I've the pool has been perfect at $10/Mo costs on my 12,800 gal pool. I also got it with heavy rains of hurricane season so I "auto-drained" my pool by reducing levels quite often. So I quickly got my CYA level in good shape. Here's the thing. The sooner you get your pool balanced the better off you'll be. Your test results are probably very accurate, you just aren't that confident due to inexperience with the more difficult test in your kit. High CYA does not mean you will immediately have a green pool. It does mean you're at (much) greater risk and it's not being properly disinfected if it gets contaminated with pathogens. My concern is that you could have a really nasty problem to deal with next year when you open. So if at all possible you should get it balanced asap. Also, can you please fill in your signature information at the bottom? It will help people provide better advice without cycling through several turns on the thread.

Again welcome, it's always great to have another engineer! I hope this is helpful.

Chris

 

[Richard320]

Been there, done that.

My pool was also in the 220-240 CYA range and draining was impossible... I would have had to pay hefty fines as well as had a restrictor placed on my meter at my expense.

So stock up on FAS-DPD reagents. That's the only way to test the FC levels high enough that you'll be able to maintain proper FC/CYA ratios. Tip: poolmath will give you minimum and targets no matter what you enter for CYA, so if you're off the chart, use PoolMath.

Whenever you get the chance to replace water, do so. Do you have a lawn? Water with pool water and use the irrigation water in the pool. Expecting rain? Direct the rain gutter downspout into the pool. Let the first half inch or so wash the roof off, then capture the rest. I get a 3:1 pool:rainfall that way

Eventually, you will get CYA down to a respectable number and pool maintenance is a whole lot easier. Until then, don't let algae get started. You'll use a whole bunch of bleach taking FC up to where it should be,m but the daily losses will be about the same as they would be at a lower CYA level. The pH test will always be suspect. The high FC reacts with the reagent itself, turning it bright magenta and leading you to believe it's somewhere off the top of the scale, so add your drops, invert to mix, and take the reading immediately. It may change later, but ignore that. Use the immediate pH result and it'll be real close to reality.

The other thing to be aware of at the high FC levels you'll need to run is the TA test may go to blue>yellow instead of green>pink. Run the test the same. The result will be valid.

Oh, and Welcome!

 

[NewWorldViking]

Thanks for the responses everyone. I appreciate the advice & confirmation of my research.

Richard320: I hear you on replacing water whenever I can but that isn't going to work. I don't have a lawn, just desert tolerant landscaping. I also have a <1 mo old new roof that is still shedding grit and whatever else a new roof leeches into the water. But that is moot as I only average 0.75" of rain for the entire month of August. If a thunderstorm does roll through most or all of the rain evaporates before it hits the ground. It's a strange phenomenon, you can tell it's happening when you see active storm clouds overhead but they only produce a cool downward breeze.

Turns out my non-scientific wife is not comfortable adding that much chlorine to the pool. I understand why but I can't convince her that it won't ruin her favorite bathing suit or her hair. (Uff Da!) I'm hitting up all my contacts for water. At least she is forcing me to have a much easier time with balancing the pool water! The pool calculators say replace 87% of the water. I'm thinking a complete replacement since I'm nearly there anyway and I read that CYA can hide in the cement and leech back into the fresh water.

This brings me to a new question which may be off-topic for the water treatment forum. Should I have any concerns about doing a full drain of my pool (structurally) if I refill it immediately? Is there anything else I might want to do while the pool is drained?

Setsailsoon: Nice name! I sail too, bareboat charter. Thanks for the heads up on the signature.

- - - Updated - - -

Hmmm. Except my signature doesn't seem to be showing up. Here it is.

Pool: 16,100 gal in-ground plaster, 26+ yrs old, full sun @ mile high desert altitude, 1 skimmer & bottom drain, Pentair WhisperFlo Pump model 196232, Pentair CCP420 filter, Pentair Mastertemp 250 heater, Pentair Model 300 Auto Chlor/Brom feeder.
Spa: Bullfrog model 562, mfg 01-01, 360 gal, 2 Bigfoot-56 pumps model PUBFC2152582F, Balboa System 2000 LE heater, jet packs & tubing refurbished or replaced 2018.

 

[mknauss]

The myth that CYA hides in the plaster is just that, a myth.

I doubt you have near surface ground water. So floating the shell should not be a concern. Confirm that however.

Bigger issue is plaster should not be let to dry and heat up in summer sun.

You can exchange some water without draining.

If you place a low volume sub pump in the deep end and pull water from there while adding water in the shallow end (through a skimmer or into a bucket on a step so you lessen the water disturbance) you can do a fairly efficient exchange. That is assuming the water you are filling with is 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 on bottom) and pull water from the top step.

The location of the pump and fill hose may change if you have salt water, high calcium, etc.
In my pool, with saltwater and high calcium when I drain, I put the pump in the deep end and hose in shallow end. The water in the pool weighs more per unit volume than the fill water from the hose.

Be sure to balance the water out and water in so the pool level stays the same. Also be sure your pool pump is disabled during this process. Once started do not stop until you have exchanged the amount of water you wish.

 

[cfherrman]

I had 28 FC and swimming in it earlier this year, didn't even smell or feel.

If you had 80 fc in your pool with 200 cya it still would feel less like clorine than the city pool with 0 cya and 1 ppm FC.

 

[NewWorldViking]

I'm on a steep, tinder dry mountainside on a ridge with dry valley creek beds 1/8th of a mile to either side of me. I definitely don't have near surface ground water.

However, dry, heat and summer sun I have in abundance. I just checked the cement around my pool in full sun. 138 degrees and it was overcast this morning. Combine that with the 17% humidity air... my plaster will be baked bone dry in no time. Thanks for the heads-up! Not drying out the plaster makes sense to me, it will have to be a water exchange. (You wouldn't believe how much stronger the sun is with 1-2 miles less atmosphere to penetrate. When I'm over 8000' elevation I use sunblock in January to avoid silly looking "goggle tan".)

How does CH play into water density? My fill water will likely be 15-20 degrees cooler than pool water so that leads me to fill low, drain high. However fill water CH is 220ppm, pool water 320ppm. Will that change my fill low, drain high strategy?

 

[NewWorldViking]

cfherrman: I'm sure you're right. But you know how it is, I'm her husband therefore I'm obviously wrong and should not be trusted.

 

[mknauss]

With your water temperature variation do the fill deep drain high.

You need a sub pump, 1/4 or 1/3 hp from Harbor Freight, Amazon, etc. I run the hose from the pump to the sewer cleanout.

My CH is normally 1000 ppm or higher with 3500 ppm salt when I drain so I do the opposite.

I know all about high elevations, lived in Wyoming for a number of years in my college and working years.

 

[NewWorldViking]

Thanks, mknauss. I'm using my very 3-dimensional land to my advantage and draining with siphons, draining high while filling deep. 2 siphons the same diameter as my fill is keeping my water level fairly stable. I'll keep this up for a while and retest.

Wyoming. Good place! And thanks to all.

 

[mknauss]

It will not be accurate to test for CYA until you stop the process and run the pump for several hours.

You could test the effluent (what you are siphoning) and if the CYA has dropped to near 0, your exchange has been completed.

Most hoses run at 5-7 gpm. So it will take nearly 40 hours to exchange your volume.

 

[NewWorldViking]

Thanks to all, the advice I received worked perfectly! This is an excellent forum.

The water exchange method worked surprisingly well, filling low w/ cold water and draining warm water high. I could tell how "full" my pool was with new water by taking temperature readings at particular depths. The effluent always had high CYA until it plummeted. After mixing things up with the pool pump for 2 hours I retested with the following results.

CYA = 20
CH = 260
pH = 7.4
TA = 130
FC = 0.8
CC = 0.1
Temp is now an invigorating 58 degrees. (As my username implies, I'm gong to love this while it lasts!)

Not perfect yet, but I still have a bunch of those evil pucks left by the previous owner. I figure I might as well use them to get CYA up to where it should be, then switch to BBB which seems to make much more sense to me as you're only adding what you actually need. I do like the convenience of the pucks but why doesn't anyone make them without stabilizer or other so-called "improvements"? It seems to me that those pucks are guaranteed to make themselves completely ineffective over time and then they'll sell you more chemicals to fix their chemicals and so on. Rather shady if you ask me. They've got to know better.

 

[cfherrman]

All solid forms of clorine are unsustainable. If your pucks are 99% triclor (no copper) go ahead and use them if you don't mind a slow cya increase.

 

[setsailsoon]

Not perfect yet, but I still have a bunch of those evil pucks left by the previous owner. I figure I might as well use them to get CYA up to where it should be, then switch to BBB which seems to make much more sense to me as you're only adding what you actually need. I do like the convenience of the pucks but why doesn't anyone make them without stabilizer or other so-called "improvements"? It seems to me that those pucks are guaranteed to make themselves completely ineffective over time and then they'll sell you more chemicals to fix their chemicals and so on. Rather shady if you ask me. They've got to know better.

Viking,

You may want to keep a few of those pucks. I keep CYA in range but leave a little room to go up when we travel. When I'm gone I load pucks in the chlorinator. Takes 2 tablets per week in my pool. I've done this for 3 weeks at a time in winter. Pucks keep pH in check too (mine normally rises due to aeration). Also worked great when I recently had knee replacement surgery and couldn't bend over too well. After a couple weeks testing and balancing the pool was like rehab!

I hope this is helpful!

Chris

PS Great to have another sailor on board! We sailed our 42' CAT 25K miles and now bare boat charter as well... heading to Bahamas in October... will use pucks for that trip as well!