NEW TF100 and BBB Convert! CYA Testing and Chlorine Help!


Jul 11, 2009
North Alabama
Hey! New to BBB method after letting the pool store talk me into using the 'tried and true method' of Tabs/Algaecide/shocking on my brand new pool (built myself last season: 18x36 Vinyl, 8ft deep end, small swimout, Deck jet fountains, 1.5hp hayward pump and sand filter). I had an algae bloom even doing everything right, so I made the switch! I ran 6% bleach according to the calc and charts on here with my best guess since I had a crappy test kit. The pool started clearing up and looking more beautiful than it had all year! :-D However I didnt feel fully comfortable without an accurate testing procedure, so I oder edthe tf100. I received it 2 days later , and I love it!

I am comfortable with all of the test types except the CYA mainly because of such a contradition with the pool store numbers on my last test about 1.5 weeks prior to receiving the tf100. They said CYA was 100 :shock: I had only had the pool open about a month with tabs, I backwash once a week at least, and barely ran it last year with chemicals in it. After that pool store reading I ran no more tabs (6% bleach only), backwashed about 3 inches out of the pool and refilled, and we had one big rain. Well I was shocked to find that my CYA reading was only 35ish. I re-read the instructions, did it again and got the same reading! How am I off so much? Did they just miss it, or not even really test it? From my testing its not even remotely close to even slightly obscuring the black dot at 100 or anywhere close to 100. I do just like instructions, fill pool water (i get it about 18" deep) to bottom of the CYA squirt tube lable, and fill to the top of the label with the large bottle of chemical. Shake a while, let sit 30 seconds, shake again and squirt into the viewing vial until I cant see the black dot while the vial is at about hip height (not sure if it should be completely invisible or just difficult to see). Here were my other readings: FC 4.5, CC .5, TA 140, PH 7.5ish (tuning my eyes to the colors). Didnt test CH because its a vinyl pool and our water is not hard or anything. I think the pool store said it was 70.

So if my CYA reading is probably accurate at 35ish, I guess next thing is to ensure I am following the chart properly now that I can read my FC levels. So Should I target my FC at around 4-4.5 right after I add the Chlorine and so it is at about 2.5 after a normal day swimming and sun? Or should I try to keep the higher 4.0-4.5 number the minimum after the day of chlorine consumption so I will have a buffer? That would require my morning number (when I add the bleach because thats when I have time) to likely be in the 6 - 6.5 range assuming the pool consumes 2-2.5 ppm per day..... Your advice is greatly appreciated!!!!

Finally, I have been adding my bleach very slowly to the shallow end skimmer (about 120ft of PVC to the pump) because we have a solar cover. I have read several threads that seem to be split on that issue, but the final outcome seemed to be that it is PROBABLY ok to add to the skimmer slowly with the understanding that it MAY do some damage to the pump seals. I do NOT have any metal in the system, no heater, etc. I would never add acid that way. I only add to the skimmer: baking soda, bleach, and I USED to add Poly 60. SO did I grossly misread this, or am I on target?


TFP Expert
LifeTime Supporter
Feb 23, 2008
Denton, TX
You can add bleach to your skimmer. Many of us do that. Just don't add acid in your skimmer. That's a big no-no.

Trust your CYA test, any test that you do for that matter, over a pool store test. You have the Lexus of testing kits. It will always be right as long as you follow the directions and take care of the reagents.

Your FC of 4 to 4.5 target is perfect.


TFP Expert
LifeTime Supporter
In The Industry
May 20, 2007
SWSuburban Chicago, IL
It sounds like you have a handle on things. I'd trust your testing over the pool store anyday - they screw that test up all the time.
Just make sure you are testing it in bright sunlight with your back to the sun, so that your body shades the view tube.

I recommend floating the jug of bleach on top of the water and pouring very slowly into the return flow of water with the pump running. Others pour into the skimmer. the choice is yours.

Your other numbers look good :)

Do you think the FC is holding overnight (just wondering if you completed the shock process after your bloom.)?


LifeTime Supporter
Jun 3, 2008
Trust your own testing. Pool stores tests are done in a manner that is quick and easy. Quick and easy is more important to a pool store owner than accuracy. If you had a line of customers waiting to purchase pool chemicals as soon as you told them what to purchase would you risk having them walk out because they did not want to wait for a water test?

I prefer to add chemicals in the deep end near a return but I have poured bleach into my pool when I had a solar cover on the pool.


Jul 11, 2009
North Alabama
Thanks for the replies! Poolmom, I am not sure about the overnight levels yet. Will test that soon. It SEEMS to me losing about 2-3ppm from after my first thing in the morning bleach add to the next morning so I think Im ok as from what I read that sounds normal. Also the pool is crystal clear and no new green stuff appearing anywhere that I see even in the nooks and crannies.

So as far as the way to target the cl levels... If my target is 4ppm should I shoot HIGHER (like 6ppm) in the morning after I add the bleach so that when it falls during the day it ends up near 4? Or should I target it to fall closer to the minimum level by starting near 4-5ppm


Well-known member
Jul 28, 2008
Agreed trust your tests. CYA is really important to maintaining Chlorine levels. I had tons of pool quality issues in the past all because I couldn't maintain my chlorine levels because I had no CYA thus all the bleach in the world couldn't maintain a constant level. Then I came here and learned about CYA and doing it right. Since then pool quality has been much better and much easier. For me the main thing is to test very very regularly -- don't wait til the water looks strange to test.

I also pour the bleach in slowly right in front of the return jet.


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