Confused Newbie needs CYA advice

Hello everyone –

I live near Dallas TX and I have a 7 yr. old pool – I had never had one prior to this so I have been going along with whatever the pool store told me to do. But this spring I haven’t been able to get the algae under control and had to shock it every few days or it would show up in the corners or sides almost overnight. When I took a sample in recently they said I had high CYA which is what was causing the chlorine to not work and that I would have to continue to add a lot of it or drain the pool and start over. I drained about a third of it the other day and refilled but the CYA was still the same as before according to the new test (over 100 ppm). I ordered the Taylor 2006 last night so hope to get that in the next few days but in the mean time I was wondering what I could be doing as I don’t want to introduce anymore CYA but the water is getting pretty green. I’d like to try the bleach to shock it but not sure how much and how often since I don’t have a way to measure the levels yet myself (but could take a sample to the store each day I suppose to get me down the road until I get the test). BTW, I found some great YouTube videos showing how to use the K2006 so I’m feeling a little empowered today and can’t wait to get going with this new program.

I also have some other issues with this pool that I hope I can tackle myself. I would like to try to re-plaster this pool in the next year or so and will be gathering information about that, and hope you have some helpful tips for me there as well.

Back to the CYA, the results of my last test were:
FAC and TAC were 0 (we had three days of hard rain and hail so I didn’t run the pump knowing I would have to shock anyway).
PH 7.5
TA 120 (I use trichlor tabs)
CYA 100
Phosphates 100

My pool stats are: 17,000 gallon in-ground pool, A.O. Smith Century, 2 speed pump, 1.5 – 2.5 HP, RPM 3450- 1725, 190 series cartridge filter.

I had read on the Pool Solutions website that I needed to take the tabs out of the chlorinator and clean that out before I add the bleach or it could explode – yikes – so will do that after I hear back from ya’ll.
Thanks a ton and look forward to hearing from you.

1. Stop using trichlor - that's why your CYA is so high.
2. Add 7 gallons of 6% PLAIN household bleach should get you to 25ppm FC (OTO orange).
3. See if you can get the HTH 6-way kit at your Walmart (check availability)
4. If not, get a cheap OTO/phenol red testkit.
5. Add enough PLAIN 6% household bleach each EVENING to bring your OTO to orange. Filter / pump on 24/7
6. Brush the pool completely at least every other day.

Let us know when you can test CYA for yourself.

Thanks, I'm off to Walmart -

Been there, done that with the high CYA, draining and refilling. I got the same results. However, CYA at 100 is still managable. One thing you need to know is that testing CYA over 100 is difficult. When you do get your Taylor Kit, you might dilute your sample 50/50 with clean tap water, then double the reading to get more accurate results.

As a general rule, the higher the CYA, the more Chlorine you’ll need. The Rule of thumb around here is to keep the chlorine at minimum of 5% of the CYA Reading. So, if your CYA reading is 100, you’ll need to keep you chlorine at or above 5 PPM.

BigDave is spot on correct with his advice. Follow those instructions, and above all else, stop using the Tablets. Each tablet adds more CYA to your pool water.

I bought enough bleach to equal 6 gallons and the OTO/Phenol red test kit. I have been running the pump this morning to keep things moving and have not taken the trichlor out of the chlorinator yet. Thought I would try out the kit right now and the results were .5 Cl and 7.5 pH.
After I clean out the chlorinator, how long should I wait to add the bleach - don't want anything to explode - but I should add it this evening, right?Then after I add the bleach, how long should I wait to test? Thanks.

If your pump is running, you can pour the bleach into the pool, right now! Just don't pour it over the trichlor in the skimmer!

BTW, AO Smith made the motor, not the pump.

Thanks - I dragged all the bleach out there and am about to start pouring. I checked the pump and there was a small label that said Hayward with an ID # and serial # but no other info so I'll see what I can dig up from the original paperwork and send that along with my new test results. Should I test immediately after I add the last bottle or wait a while?

Wait a little while to let it mix.

I just checked and the Cl is 5+ (even more yellow than the top color) and pH is 7.5. Will run the pump all night and see if it is less green in the morning. Hayward got back to me and, for the record, I have a 1.5 HP Hayward Super II pump.

Thanks so much to everyone today for all their help! Can't wait to get the kit to find out what the CYA level really is.... and what I need to do from here.

Until your kit arrives, you can use a dilution method to force your kit to read higher. Not super accurate and doesn't replace getting a good kit, but better than nothing. More about it here:

Testing Without a Good Kit

Hope this helps!