Safe Cl level to operate heater?

[skillset]

Opened last week and pool crystal clear after <48 hours. Didn't have to add Cl for a couple days as shock level came down slowly after a few days. Added CH from last year on Friday. I wouldn't have expected this to affect the water, but pool hasn't held Cl since. So, shocking now.

TA=90
CYA=50 (pool lost ALL CYA over the winter - added CYA)
FC=22 (just shocked)
Ph=7.5
CH unknown...tested at 90 a few days ago and then added what I had left of CH from last year - 7lbs 2 days ago.

I can't imagine the loss of Cl is due to adding CH, but very coincidental. Also, the guys who closed my pool didn't follow my instruction not to add anything to the pool since I add my own chems from advice from TFP. I also read the thread where the guy who lost has CYA over the winter had an ammonia issue but wouldn't think it's that either since the Cl was good for a few days after opening when I didn't have to add any.

I'm assuming shocking now will kill whatever is eating my Cl.

So, I'd like to start heating the pool later this week (it's 66 now), so at what level of Cl would you NOT operate a heater?

 

[YippeeSkippy]

I guess i'm confused as to what you did that you're calling "shock"?

Was this a one time dose of some wildly high amount of chlorine, or was it a SLAM procedure like we advocate when you need to clear your pool of algae? What exactly did you add?

The only thing *I* know of that is important with a heater is to closely monitor your pH (too low=bad!) and some calcium is good (even in pools that don't normally need calcium like vinyl). I've never read anything about FC level limits with heaters. I'll check around though....

 

[skillset]

Thanks for the reply on the heater.

Situation seems to be ok. I was just using bleach to get to and maintain shock level. Long story short, FC levels held overnight for about 3 nights, but during the days following the shock treatment, the water lost quite a bit of FC - in the double digits, which is not normal for me. I read a lot of really older posts out here and seems some have experienced this. So, as long as I was holding at night, I resolved myself not to worry too much about it as long as the pool was able to hold the minimum amount of FC for my CYA level during the day. I've had good readings the last 2 days so hopefully the pool has "stabilized" after opening. Water looks great. Thanks again for the initial reply.

 

[Richard320]

I'll address the title question first: The heater doesn't really care how high the FC level is. Most plumbing setups don't have a heater bypass, so anyone who has ever done a SLAM has run super-high chlorine levels through their heater, they just didn't heat it. When I started out with 200+ CYA, I was running 20 FC and using the heater and swimming in the pool with no problems.

As for the sudden chlorine demand: something is still growing in your water. Sounds like this situation: Think I may have found my FC demand issue?