I've been using 8.25% bleach as my chlorine source for the last couple of weeks after coming out of a situation in which CYA got too high after trying to combat an algae problem. I now use a TF-100, and the CYA/chlorine chart said to keep FC around 6 with my current CYA level of 50. Each time I add more bleach to get my FC level up, it raises my pH as well. I'm concerned about raising my pH too high. I've never had to lower my pH (challenge has always been keeping it up to a good level), but if I start using muriatic acid to lower it, will that affect my FC level?
Adding Bleach Raises pH Slightly
- Thread starter PoolFrog
- Start date
I don't think it is as much the bleach raising the ph as it is the lack of the ph lowering effects your previous chlorine source had (I am guessing trichlor pucks). Your ph tends to increase with time due to swimming and splashing, so needing to lower your ph occasionally is not a big deal.
Good luck!
Good luck!
Thanks! I've never had to get muriatic acid before. Where is the best place to get it? Is there a particular brand that I should look for (or avoid!)?
I get mine at the local hardware store. Just make sure you are getting 20 baume and be careful with it. It's some pretty serious stuff!
First, how high is your FC when you are testing pH? Also, I assume you are using the color block (phenol red) pH kit? High Chlorine gives false high pH on that test. Can we see a full set of numbers please? Bleach pH is high, but the conversion and breakdown is a net acid reaction. It wont raise your pH long term.
When you increase the FC level using a hypochlorite source of chlorine (bleach, chlorinating liquid, Cal-Hypo, lithium hypochlorite), the pH will rise. However, when the FC drops back down from the chlorine being used/consumed, the pH will drop back down as well. Over time, a pH rise usually comes from carbon dioxide outgassing and that occurs more if the Total Alkalinity (TA) is higher, so what is your TA level? Perhaps you need to lower it some.
Also, it is not uncommon to have to add some acid every now and then. If your TA isn't too high, you may only need to add it once a week or two or perhaps even less. If you need to add it more frequently, then your TA is probably too high or you have significant water aeration sources (fountains, waterfalls, spillovers, etc.).
Also, it is not uncommon to have to add some acid every now and then. If your TA isn't too high, you may only need to add it once a week or two or perhaps even less. If you need to add it more frequently, then your TA is probably too high or you have significant water aeration sources (fountains, waterfalls, spillovers, etc.).
Below are my test numbers from last night:
FC = 3 (added bleach last night, now FC = 7)
CC = 0.5
TA = 80
CH = 140
CYA = 50
pH = 7.5
I didn't realize that my chlorine was so low (I had been testing this week, but I'm still getting used to the TF-100 and forgot that you're supposed to multiply by 0.5 when you do the Chlorine Drop Test - feel like an idiot), so I added some bleach last night which brought my FC up to a 7 this morning.
The low chlorine level that I've had all week certainly explains the greenish tint that had come back to my water, so I added more bleach today to bring the water up to shock level. Chlorine/CYA chart said my shock level is 20. According to the Pool Calc., I only had enough bleach on hand to bring FC up to 18, so that's what I've just done. Hopefully that works to clear up the water. Is it likely that I'll have to add acid to lower the pH after putting so much bleach in?
FC = 3 (added bleach last night, now FC = 7)
CC = 0.5
TA = 80
CH = 140
CYA = 50
pH = 7.5
I didn't realize that my chlorine was so low (I had been testing this week, but I'm still getting used to the TF-100 and forgot that you're supposed to multiply by 0.5 when you do the Chlorine Drop Test - feel like an idiot), so I added some bleach last night which brought my FC up to a 7 this morning.
The low chlorine level that I've had all week certainly explains the greenish tint that had come back to my water, so I added more bleach today to bring the water up to shock level. Chlorine/CYA chart said my shock level is 20. According to the Pool Calc., I only had enough bleach on hand to bring FC up to 18, so that's what I've just done. Hopefully that works to clear up the water. Is it likely that I'll have to add acid to lower the pH after putting so much bleach in?
Review the SLAM procedure, it is not a one time elevated FC. You must maintain the FC at shock level until you pass the three criteria to stop.
No. Always test pH before you add the chlorine, which you did. Your pH is 7.5 and is perfect. You should not test the pH if FC is above 10, as that will skew the test to a false high reading.
Your pool is green? You are planning to do the SLAM process?
It's not totally green, but when I was sweeping some debris last night, I started seeing green clouds coming up off of the bottom. It's not feeling slimy. I hoped that increasing the chlorine to shock level would take care of it.
PoolFrog said:
Nope, it takes time and exposure to kill it all. It is why we promote the SLAM process, and we don't say go shock you pool like pool stores and pool "pros" say it.
It is a PROCESS of time and elevated FC until everything is completely killed off. Please read through it and begin one yourself. Sounds like you really need it. Ask questions if you need to but check it out and get a SLAM going.
Sweeping or brushing will really help clear up the pool , along with the higher FC levels. Keeping your FC at SLAM levels will vastly improve your results. If you want, you can test every hour as long as the FC is consumed rapidly. If you used a 5 ml sample for your FC testing, you will use half as much reagent but you lose precision.
Yet, as long as the pool is not so cloudy that you could not see a swimmer, up to shock level is fine .PoolFrog said: