how does a high FC affect PH readings? As I was wasting my water while vaccumming the pool in order to drain for refill tomorrow, I could tell that although my pool looked clear to the naked eye, with my sunglasses (polarized) I could see that my pool did have some light brown film (algae i assume) on the liner. So I stopped and dumped in 2 1/2 gallons of liquid chlorine, just to prevent it from getting worse overnight. Is that ok? Also have another problem...when my husband was vaccumming the pool the other day, he forgot to put the backet back in the return. So has anyone had a clog in their pipes before? and if so...how did you get it out? We were told not to "snake it out". My husband tried to blow it out,but it didn't work. We are pretty sure there is something in the one pipe because when we close the other returns, there isn't much water entering the basket. Any suggestions? Thanks.
Please Help Me
- Thread starter dbabz31
- Start date
FC above 10 starts to cause the PH to read higher than actual, off by more the higher the FC level gets. Once FC gets up to somewhere around 20, the PH reading starts being wildly wrong.
holy cow! i waited 45 mins after adding the 2 1/2 gallons of liquid chlorine and retested my FC...yikes! 17! I guess that it is ok considering that my cya is so high anyways, and with the drain that I need to continue and refill tomorrow I should be fine. Right? I hope so.
Ok i have new results! We drained some of our pool, decided to only do 1 truck load which brought our water level up to the minimum level need at skimmer. (another truck load would have been too much and they would have charged us the full amount whether we used it all or not. Supposed to rain more the next few days so should add a little more for us.) I let the water circulate for 2 hours and have just retested my levels and compared them to last night's level(prior to draining) and here they are.
LAST NIGHT-7pm NOW
FC=14.5 FC=10.5
CC=0.5 CC=<0.5
PH=8 PH=7.9
TA=260-280 TA=260-280
CH=110=120 CH=100-125
CYA=greater than 100, more at 150,but hard to say CYA= 90-110 (did it 3 times, after a while i swear i am seeing black dots everywhere.
So I figure with the extra water we still can and need to add, our CYA levels will be just where I want them. We have direct sunlight on our pool with no shade at all until sun goes down..so I think I should keep it around 80. So, do I wait and retest in the morning? See where my FC levels are and shock accordingly? or do I get PH a little less and then shock?
Thanks for the advice. Will wait to hear what to do next.
LAST NIGHT-7pm NOW
FC=14.5 FC=10.5
CC=0.5 CC=<0.5
PH=8 PH=7.9
TA=260-280 TA=260-280
CH=110=120 CH=100-125
CYA=greater than 100, more at 150,but hard to say CYA= 90-110 (did it 3 times, after a while i swear i am seeing black dots everywhere.
So I figure with the extra water we still can and need to add, our CYA levels will be just where I want them. We have direct sunlight on our pool with no shade at all until sun goes down..so I think I should keep it around 80. So, do I wait and retest in the morning? See where my FC levels are and shock accordingly? or do I get PH a little less and then shock?
Thanks for the advice. Will wait to hear what to do next.
Can I ask why? Is it because high chlorine will raise PH? or will give false high PH levels? Do you think that with adding more water would lower the PH? I really could add a little more water if needed. Otherwise I am going to add less acid than the calculator states because my total volume is less than normal right now right?
the pH adjustment is because over time, pH usually rises due to aeration, etc...
The increased FC makes accurately measuring pH difficult, so we usually start low pH and ignore through the shock cycle1
The increased FC makes accurately measuring pH difficult, so we usually start low pH and ignore through the shock cycle1
Lower ph first, add 2/3 rds of what the pc says. Run the pump for 45min to 1 HR then retest for ph. Then Add MA as needed to get to a ph in lower 7s. High fc will cause false ph, take care of ph first... Then start the shock process. If you are adding cya that is not liquid it will take more than 1'hr to register on tests...
Ok, I understand. But if I add more water to my pool will that bring the PH down also? I guess if I go too low by accident with the PH I can increase with aeration. Can I just turn my slide on for that? and if so, how long do I let it run. Don't plan on having to aerate, but if I need to sometime, it would be nice to know. Thanks.
If high fc causes false PH, in what way is it false? too high,to low of readings? my fc right now is 10.5, so do I wait for it to come down to normal before i adjust ph? If my chlorine levels remain the same overnight tonight, then is the shock process necessary?
As Jason wrote earlier, it would read falsely high. More info on this from Taylor Technologies is in this post. As the FC level drops, the pH may drop as well since chlorine usage/consumption is acidic. On the other hand, with your CYA level so high, you need a high FC level to prevent algae growth so that's a bit of a catch-22. I'd say, have the FC get down to just below 10 ppm and then adjust your pH. Of course, things will be easier to manage at a lower CYA level.
Given how hard it is to lower the CYA level you can see why it's much easier to prevent the problem by not over-using stabilized chlorine (e.g. Trichlor or Dichlor). Most of us have been through this hard lesson, but at least we only go through it once after we learn the truth.
Given how hard it is to lower the CYA level you can see why it's much easier to prevent the problem by not over-using stabilized chlorine (e.g. Trichlor or Dichlor). Most of us have been through this hard lesson, but at least we only go through it once after we learn the truth.
you are right! no one ever told us anything about cya. but i guess it is something that i had to learn. should i wait til tomorrow, recheck everything, see if my fc comes down and then get a more accurate ph reading? add ma if needed and so on? If I add MA, I leave the pump running the whole time right? That's what it says in how to lower TA, so assume when you add it, it's the same process whether you add it for PH or TA.
dbabz31 said:
Your current ph reading is 7.9 and your FC is 10.5, correct? that's not so high that it would make a big difference in the PH. I would go ahead and lower the PH with MA - dose to 7.2. yes leave the pump running for at least 1 hour, longer is better.
so my ph is now like 7.1-7.3 hard to tell, test is more orange than yellow or pink. so now do i aerate? can i do that while i shock. or do i just shock it.
My pool is clear and my CC is <0.5, so is shocking necessary? I am just wondering if I can add chlorine daily to kkep levels where they need to be according to the cya chart.
So I dumped in 10 gallons of liquid chlorine, but now I am wondering if I should have backwashed my filter prior to dumping the chlorine in. The psi is reading 18. When should I backwash my filter? I dont want to lose all the chlorine i just put in. Thanks for your advice!
you normally backflush when you're pressure reaches about 8-10 psi ABOVE what it started at- since you don't have a reference point right now, gauge it based on return; if your return is still strong, good water flow, don't worry about the backflush.
Next time you need to backflush, note the pressure when you finish- this will be your reference starting point for the next time to flush!
Next time you need to backflush, note the pressure when you finish- this will be your reference starting point for the next time to flush!