Pool chemistry - just getting started - overwhelmed with reading past posts

sasperger

Member
May 2, 2020
6
Tucson, Arizona
Hello!

I joined this group about a week or so ago and have been reading many past post so I don't repeat too many questions. I have the Taylor 2006 DPD testing kit and discovered several things:
- that I was using the wrong end of the scooper for the powder (so add me to the statistic as well)
- that my CYA is extremely high and have to change out my water
- that I am not very good at math or chemistry and struggling a little with the pool math app (I'll figure it out eventually - just a little slow)
My test results are: (tested at 5pm 5/9/2020)
FC: 7.0 (I added about 64oz liquid chlorine at 8am after I had a FC reading of 1.5)
CC: 0
PH: 7.6 (not sure accurate after adding LC)
TA: 175
CH: 925
CYA: 100+
My water is crystal clear and I can see all the way to the bottom. I don't see signs of green or algae. I have pebble tec. The pool is 80 degrees. I've skimmed out all the sheddings from the trees, brushed and vacuumed. I seem to be skimming the pool at least 3-4 times a day.

Before I took over managing my pool (and we'll see how it goes) the companies I had caring for my pool never told me that my CYA was high. They were using the "pucks" and have been for at least the 2 years we have been here. Why wouldn't they tell me that these were high and I needed to change my water?
Reading past posts and the SLAM - seems like I am going to need a very high chlorine level to offset the high CYA before I can get the water changed. I live in Tucson, and not ever having done this am going to need some help and have to figure out who can help me and how to drain my pool. With it being extremely hot already, I would like to talk to the water company to make sure it is not going to cost a fortune to refill the pool.
Short of changing the water...in the meantime....what do I need to do to make it safe for swimming? If I understand correctly CYA is acid, so we would basically be swimming in an acid bath? I greatly appreciate your knowledge and assistance.
Thank you, Shannon
 

tim5055

Mod Squad
TFP Expert
LifeTime Supporter
May 11, 2014
10,928
Franklin, NC
Welcome!!

Most don't tell you about pucks because they have no idea that a puck is almost half stabilizer. The rest don't care. If you get algae that another service and special chemicals to sell.

Why are you talking about a SLAM, did I miss something? If the water is clear and you don't have visible algae there is no need to SLAM.

Get in the water and swim. It's safe. When I took over my pool from the previous owner the CYA was around 250 and I had to keep the chlorine around 20....

Oh, as long as your FC is below 10 assume the pH reading is correct. It only goes high as the FC goes above 10.

Now, we need to narrow down your CYA so you can keep the correct amount of chlorine in the water.

100 is the limit of the CYA test, so you have to do a diluted test. While the full instructions are in the Pool School, here is the short version. Mix 50% pool water with 50% tap water. Use this mixed sample as your test water. If still at a 100 you will need to dilute more. The problem is that when doing a diluted test not only do you multiply the rage of the test you multiply the error rate of the test, so results are a ballpark - not an absolute. Here is a great chart by JamesW to explain dilution rates and what you multiply the results by to get an approximation of your CYA level.

Pool water......Tap or distilled water.........Multiply result by

....1........................1................................2
....1........................2................................3
....1........................4................................5
 

tim5055

Mod Squad
TFP Expert
LifeTime Supporter
May 11, 2014
10,928
Franklin, NC
I'm going to let some of the folks from the SouthWest talk to you about you high CH and how to deal with it. When you do a water exchange it will come down some.

You are lucky. You live in Tucson. You have another option for removing that CYA and CH. It's called "Reverse Osmosis" which is a treatment using a machine to pull those chemicals out of the water.

I have no idea if these guys are good guys, but a quick Google search found them. You may have to do a little research, but it's another option.

 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
23,645
San Dimas, CA (LA County)

sasperger

Member
May 2, 2020
6
Tucson, Arizona
Welcome!!

Most don't tell you about pucks because they have no idea that a puck is almost half stabilizer. The rest don't care. If you get algae that another service and special chemicals to sell.

Why are you talking about a SLAM, did I miss something? If the water is clear and you don't have visible algae there is no need to SLAM.

Get in the water and swim. It's safe. When I took over my pool from the previous owner the CYA was around 250 and I had to keep the chlorine around 20....

Oh, as long as your FC is below 10 assume the pH reading is correct. It only goes high as the FC goes above 10.

Now, we need to narrow down your CYA so you can keep the correct amount of chlorine in the water.

100 is the limit of the CYA test, so you have to do a diluted test. While the full instructions are in the Pool School, here is the short version. Mix 50% pool water with 50% tap water. Use this mixed sample as your test water. If still at a 100 you will need to dilute more. The problem is that when doing a diluted test not only do you multiply the rage of the test you multiply the error rate of the test, so results are a ballpark - not an absolute. Here is a great chart by JamesW to explain dilution rates and what you multiply the results by to get an approximation of your CYA level.

Pool water......Tap or distilled water.........Multiply result by

....1........................1................................2
....1........................2................................3
....1........................4................................5
Thank you! I will give this a try. I wasn't sure if I needed a SLAM since I was opening the pool, or because my CYA....guess I got mixed up with all the information. So a SLAM is only if your pool is green? ok...so I did a diluted test and had to go to the 1:4 ratio and it was at the 100 line, so if I multiply that by 5...does that mean my CYA is 500?!?! Yikes! I really hope I am doing it wrong then, or maybe I need a more reliable test for CYA. Last time I took it to Leslie's was in March (before I got my own kit) and they had a CYA reading of 150. They've had CYA reading from 100 up to 190.I'll have to do some more research on this site regarding CYA.
 

sasperger

Member
May 2, 2020
6
Tucson, Arizona
Just by seeing your TA and CH readings, I knew you were in Tucson.
Since you are in Tucson as well and you probably have your CYA under control using LC, should I need to drain my pool or exchange the water - who do you recommend or what is the best way? I want to call the water company to see what a fill of about 5K or 6K gallons of water will end up costing. I just don't know how to do the draining part.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
29,846
Laughlin, NV
I would suggest a full drain/refill or water exchange.
See Draining - Further Reading

I suspect you have no shallow water table issues. Correct? If so, then renting a sump pump from Home Depot with whatever hoses you need to direct the effluent is your best method. You should have it empty in a few hours. Start in mid-afternoon. Once drained, start filling with your tap water as quickly as possible. Will most likely take over night.
 

tim5055

Mod Squad
TFP Expert
LifeTime Supporter
May 11, 2014
10,928
Franklin, NC
As you are now int eh full drain club, look intothe Revrse osmosis. Not sure what they charge but compare their cost to the water and drain/refill hassle.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
29,846
Laughlin, NV
RO normally runs around $1000 plus you still need to make up about 20-25% of your pool volume in additional water.
They will 'balance' your pool water after, as add some calcium and stabilizer.
It is a choice.
 

DanF

Silver Supporter
Mar 17, 2019
132
Chandler, AZ
You are fortunate that you have a pebble-tec pool as opposed to plaster. PebbleTec can be drained pretty much any time of the year here in AZ but plaster will crack if you drain after Feb/March.
 

chiefwej

LifeTime Supporter
TFP Guide
Jun 12, 2011
3,477
Tucson
The water cost for drain and refill in Tucson is way cheaper than RO treatment. My pool is 19k and refill water bumps my water bill by less than $100. It actually cost me more for salt and other chemicals to rebalance than for the water itself. Just never do a refill in November, December, or January. They use consumption figures during those months to set your sewer rates for the next year. So that would increase every monthly water bill for a full year.

I use a Salt Water Chlorine Generator (SWG), not liquid chlorine. Most of my neighbors either originally had salt pools or converted to SWG. It’s a lot more convenient than lugging and measuring liquid. I have also connected my pool’s auto fill to a water softener to control CH. Dealing with Tucson water can be a challenge, but there are ways to make It just a bit easier.