First time opening - CYA and CC question

May 3, 2017
Indianapolis, IN
Last summer was my first time owning a pool. That time I had someone professionally open and close it, mostly because that same person installed a brand new vinyl liner. This year I decided to open and close myself.

When I took off my cover Sunday (three days ago) the water was practically black. Just before I'd had the water tested and these were the results:
FC: 0
TC: 0
CH: 140
CYA: 0
TA: 110
pH: 7.8

Since then, I've added 16oz of algeacide (split between two different 8oz doses on different days) and also 4 lbs of cal hypo powder (split between 2 2lb doses on different days.) As of yesterday the water was a nice turquoise color instead of black, though still very cloudy. I have about 2.5 ft visibility in it. I had been running the pump 24 hours that entire time (had to backwash once) until last night. So the pump ran 24hrs for almost three days. I've also brushed down the sides and bottom three times in the last three days.

I made the assumption that the cloudiness was more algae, so last night I decided to try that HTC Green to Clear product. This called for me to turn the pump off. It worked in raising the dead algae to the top and then sinking in, but of course now I can't see the algae because it's all dead at the bottom and water is still cloudy.

That's when I started doing more research and found out about Combined Chlorine, and I'm guessing that's what my cloudiness is coming from. At this point, here are my readings that have changed:

FC: 1-2
TC: 5
CC: 4-3
(I can't get the exact FC and CC count because I really have a hard time telling from my DPD test kit the color difference in the first two levels)

From researching the forum here, I can see that I probably should have used bleach instead of cal hypo to start up the pool. I still haven't added any CYA because my pool store instructions say to remove algae first.

Here's my plan moving forward: I plan to vacuum out the dead algae as best I can, turn the pump back on to filter, and begin adding bleach on the SLAM procedure.

1: Should I actually begin adding CYA now instead of waiting?
2. Through several comments from JasonLions on this forum, I was finally directed to this thread:
Please Explain Breakpoint and of Sodium Hypoclorate
This seems to debunk the 10x rule for CC. Using my numbers, what should be my target shock level? I'm still a bit confused on that. And I really want to get this right because I just installed my liner last season and am mortified at the idea of burning it up.
3. Is the rest of my plan sound? Should I try to vacuum the algae off the bottom first or just wait til the water clears up first?

Any help is very much appreciated.
May 3, 2017
Indianapolis, IN
Thank you for your reply. I have a DPD test kit that tests free chlorine, total chlorine, pH, and alkalinity. Is that one of the two suggested?

I found the CYA chart yesterday. The reason I posted my question is because there are no entries on it for 0 CYA. Am I to assume that means I should begin adding CYA despite algae most likely being present in my pool? It's not completely clear yet, there's a small tint of green to it. So I'm assuming there's still some algae in it.


Mod Squad
TFP Expert
LifeTime Supporter
Apr 17, 2010
East Texas
What you are looking for is a fasdpd FC test kit which is comprised of a powder and a liquid that can ACCURATELY measure to 50 ppm FC in .5 increments. TF100 or Taylor K-2006C. Use FC of 10 for CYA level of zero.
May 3, 2017
Indianapolis, IN
New question: how long do people typically wait to test the water after they've shocked the pool? I'm seeing a lot of different answers on the forum.

According to the calculator here, I was required to dump 324 oz of 6% bleach into my pool to attain 10ppm FC. The bleach I bought from Aldi last night said 8% and I put in 384 oz. I did a quick brushing of the sides and swished the water around with my pool brush to hopefully mix it up a bit quicker. I did a reading right after that and it looked like my free chlorine was only a 3 instead of a 10. Then I did a reading about an hour later and it looked about the same. Did another one this morning as part of an overnight test (turned off the chlorinator) and it looked like it sank to maybe a 2.

At any rate free chlorine is nowhere near the 10ppm required. Any ideas why that might be? Maybe the bleach is junk or possibly the test? It has been raining a lot at my house, but I don't know if that's enough to mess with it that much. It looks like my TC is up around 10ppm.

Mr Bruce

TFP Guide
Mar 24, 2014
Greenville, SC
You are not going to be able to do this without an FAS-DPD test. So you might as well just add a gallon of bleach a day with the pump running until you get one. Well, that and get as much debris off the bottom as possible.

To answer your question though, bleach is going to be quickly consumed, especially in a black pool. You will need to test and add frequently.

I suggest adding a gallon of bleach a day and keep refreshing the tracking page on your FAS-DPD test :)
May 3, 2017
Indianapolis, IN
Yeah, I've got one ordered. Pool's actually no longer black. It's blue but just really cloudy and still can't see the bottom.

Just to make sure I'm understanding you right: when you say the bleach gets consumed quickly - do you mean like within five minutes? Because that was the amount of time that elapsed between when I dumped it in and tested.


Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
Sebring, Florida
You should read the SLAM article and follow that to clear your pool. What you are doing now is sortas' stopgap and may or may not get you swimming.
May 3, 2017
Indianapolis, IN
Thanks. I have read the slam article numerous times and understand that I need to wait for my better test to arrive (again, it's been ordered) before I can do it accurately. I'm still wondering if it's possible for a pool to drop 7ppm FC within five minutes.
I got my FAS-DPD test Saturday and started following the SLAM process. I've been adding bleach to bring up to shock level as often as possible for me. Saturday I shocked six times starting around 1pm and yesterday I shocked four times starting 7:30 am. I brushed down the sides of the pool once on both days and the pump/filter have ran continuously.

The combined chlorine was falling nicely, drastically at first and then slower. But now it's started to come back up. It was 7ppm when I started SLAM on Saturday. It hit it's low yesterday at my 4:30pm reading where it was .4ppm.

After that I added water from my hose because I wanted to do more sweeping of dead algae and debris on the bottom today. After the water addition, my next test was yesterday at 9pm and the combined chlorine went back up to .6ppm. When I tested the water this morning at 6am it was up to 1.2ppm.

Has this happened to anyone else before while they were SLAMing? Is it possible that adding water created more combined chlorine in the pool, or does this just happen sometimes? I never had a combined chlorine problem all last summer so this is something new for me.


TFP Guide
Apr 12, 2016
Tucson, AZ
You don't have to use the 25ml water sample for the FAS/DPD test - this is actually a waste of reagent for most uses.

Use a 10ml water sample, and divide the number of drops by two to get your result. This will save you a lot of reagents - critical when you're slamming.

CCs are a result of the chlorine working. They are removed from the pool by sunlight breaking them down. Don't stress too much about them going up or down, just keep SLAMing until the SLAM end requirements are met.
Use a 10ml water sample, and divide the number of drops by two to get your result. This will save you a lot of reagents - critical when you're slamming.

CCs are a result of the chlorine working. They are removed from the pool by sunlight breaking them down. Don't stress too much about them going up or down, just keep SLAMing until the SLAM end requirements are met.
Cool, that helped put my mind at ease. I was starting to worry I was doing something wrong when they started going back up again. Thanks for the informative answer.


Bronze Supporter
May 1, 2016
Naperville, Il
When SLAMing (and only when SLAMing), I use a 5ml sample. I got a $3 medicine dropper at Walgreens that lets me get a very accurate 5ml level of water. That gives me 1 drop per 1 ppm FC level. That is plenty accurate when checking high chlorine levels during a SLAM, and saves a ton of reagents. Once the SLAM is over, I go back to the 25 ml testing.
SLAM complete! Passed the SLAM conditions yesterday morning and began routine maintenance last night. Just wanted to thank everyone on the forum who helped out with suggestions here. You definitely saved me a lot of time, money, and guess work.

Pool went from this:
To this:

It only took a small amount of bleach. *sarcasm
5 days from black to clear. That's pretty impressive.
Oops, should have probably been more specific. It was actually about ten days. The first five days was before I came on here and started asking questions, though. There was sporadic, random back and forth progress during that time. Once I actually figured out what I was doing and got help from you guys (the latter five days), progress was way more steady and constant.

Also, Texas Splash, love the Bill Murray badge! Bill Murray is amazing.