Confused FC/CYA

[Branch Fly]

In March of this year we had our first pool installed (18'x54" AGP). I have been on TFPC since installation and have been very happy. In late June or early July my water temp was consistently above 90 degrees and we had a low level algae bloom with CYA at 30 ppm and targeting 4 ppm FC. After a slam, I followed the advice of others on this site and increased to CYA of 40 ppm and targeted FC of 8 ppm with a minimum of 4 ppm. No problems, but I did have to go to 8.5 ppm FC every night to maintain a minimum of 4ppm FC because I get 12 to 13 hours of sun per day.

This week, we had a small amount of green algae in the areas of the pool that has slower flow when the pump is on. I'm running the pump 9 hours per day on high and have a cartridge filter. The filter is clean. The kids have only been swimming about once per week because of school and extra curricula activities. I try to brush once per week, but got behind on it. I slammed and after two days I passed all criteria and was done. Today, I went to the pool store to kill time and they nearly dropped dead when I told them that my FC is brought up to 8.5 every night to maintain a minimum of 4. They suggested raising the CYA to 80 and getting back down to an FC of 3 or 4 ppm. I talked to a friend of mine who maintains pools and he was less concerned. He did feel that I should bring the CYA to 50 or 60 and so my FC will not swing so wildly. He feels that I should be targeting and FC of 5ppm and a minimum of 3 or 4 ppm.

I'm usually adding 46 ounces of 8.25% bleach per night. I'm spending about $6 per week on bleach. Had to SLAM twice from March of this year to now. Am I adding to much chlorine and is my CYA too low?

 

[tim5055]

Today, I went to the pool store to kill time and they nearly dropped dead when I told them that my FC is brought up to 8.5 every night to maintain a minimum of 4. They suggested raising the CYA to 80 and getting back down to an FC of 3 or 4 ppm. I talked to a friend of mine who maintains pools and he was less concerned. He did feel that I should bring the CYA to 50 or 60 and so my FC will not swing so wildly. He feels that I should be targeting and FC of 5ppm and a minimum of 3 or 4 ppm.

Ignore the pool store. They are giving you old stock information that is not based on the reality of the CYA/FC relationship.

You friend is closer to reality. With the amount of sun you get your CYA should be at the top of the recommended range which is 50. With 50 CYA your target is six, minimum is 4.

If you hqave areas of low circulation either you need to figure a way to improve it or brush those areas a little more regularly to get chlorine in the area.

 

[pwrstrk]

I agree with Tim on everything except the target FC level , I'm going to suggest you target 7-8 and don't let it fall below 4. That gives you more wiggle room so you don't fall below your min of 4. Pool math would give you a target of 8 for a CYA of 50. ?

 

[tim5055]

I agree with Tim on everything except the target FC level , I'm going to suggest you target 7-8 and don't let it fall below 4. That gives you more wiggle room so you don't fall below your min of 4. Pool math would give you a target of 8 for a CYA of 50. ��

Well, we need to update the FC/CYA chart in the Pool School



But, with all the sun I can agree a little more wiggle room would be nice.

 

[pwrstrk]

I know. I personally feel 2 ppm isn't enough wiggle room. I never suggest that. I don't to it myself My CYA level is 40 and I target 7. Pool math gives the same target. ?

 

[tim5055]

I know. I personally feel 2 ppm isn't enough wiggle room. I never suggest that. I don't to it myself My CYA level is 40 and I target 7. Pool math gives the same target. ��

I know what you are saying, but I'm too new to deviate too much from published sources. I leave that to the senior folks...

 

[pwrstrk]

It can be brought up. It's the USA !!
I look at it as it's playing it safe that way. I know people sometimes forget to bump FC levels up if the pool is getting heavy use and if you have a bunch of kids swimming like I have you know accidents are going to happen you have your butt covered with FC. Sometimes I can go a day if the weather is right and the pool sees little use, without having to add bleach. ?

 

[Smykowski]

It can be brought up. It's the USA !!
I look at it as it's playing it safe that way. I know people sometimes forget to bump FC levels up if the pool is getting heavy use and if you have a bunch of kids swimming like I have you know accidents are going to happen you have your butt covered with FC. Sometimes I can go a day if the weather is right and the pool sees little use, without having to add bleach. ?

^^This^^

I operate the exact same way. I run my CYA at 40 and keep my FC between 7 and 9 for all the reasons listed above.