yet another "going on vacation" question

evalm2010

Well-known member
Jun 21, 2010
56
Washington, DC
I will be out of town starting early Friday and will be back late Monday. My FC is currently at 8 (still coming down from shock level). My CC is staying at .5. My CYA is <20. My question is should I bring my FC to shock level which is 10 and overcompensate on the days I will be gone? Like if I know I lose 2 ppm during the day and 1 ppm at night should I then bring up my FC to say 22 and hope that it will still be at shock level by the time I get back? Is an extremely high FC bad for a plaster pool?
 

dmanb2b

TFP Expert
LifeTime Supporter
Apr 4, 2009
3,734
NY
With CYA at less than 20, your FC will come down fairly quick....it may help using a floater with tri-chlor tabs since your CYA is so low.

Also you mentioned you are losing 1ppm FC at night....if so, it's probably wise that you want to bring it up to shock....just not sure about going up to 20 on a plaster pool...that's almost double your shock value.

How about going to 15 and covering the pool w/ solar cover?
 

Melt In The Sun

TFP Expert
LifeTime Supporter
Oct 29, 2009
3,899
Tucson, AZ
I think dman missed that you have an indoor pool; CYA is fine where it is. Raising it to shock level would be OK, but as dman mentioned, losing 2 ppm during the day and 1 overnight doesn't sound normal.
 

dmanb2b

TFP Expert
LifeTime Supporter
Apr 4, 2009
3,734
NY
Melt In The Sun said:
I think dman missed that you have an indoor pool; CYA is fine where it is. Raising it to shock level would be OK, but as dman mentioned, losing 2 ppm during the day and 1 overnight doesn't sound normal.
Thanks Melt :goodjob: My bad on missing the indoor piece of info....CYA close to 20 is fine then :hammer:
 

evalm2010

Well-known member
Jun 21, 2010
56
Washington, DC
Melt In The Sun said:
I think dman missed that you have an indoor pool; CYA is fine where it is. Raising it to shock level would be OK, but as dman mentioned, losing 2 ppm during the day and 1 overnight doesn't sound normal.
Oh, I thought losing 2 ppm during the day is normal. What is normal for an indoor pool? Should I be shocking longer then? I stopped shocking when I passed the overnight FC loss test and my CC went down to .5. Should I continue shocking?

Thank you both for a speedy response. :-D
 

evalm2010

Well-known member
Jun 21, 2010
56
Washington, DC
I just want to add that my pool is indoors but gets a little bit of sunlight during the day. Not much but from noontime to about 3 pm, direct light hits part of the pool that's exposed to skylights. Would that make a difference?
 

JasonLion

TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
37,880
Silver Spring, MD
If the skylights are open then yes it will help. But if they have glass in them, then no it doesn't count.

You should probably make "indoors" more prominent in your signature. Our default is to assume outdoors, which has somewhat different treatment issues.

An indoor pool won't normally lose any significant amount of chlorine, day or night, unless someone swims.
 

evalm2010

Well-known member
Jun 21, 2010
56
Washington, DC
Okay, I'm shocking again tonight. I'll continue to shock at FC 10 until Thursday then I'll bump it up to 20 to compensate for my 4 day vacation. Would it make sense for me to use Tri-chlor tabs? I still have some. I just don't want to add unnecessary chemicals to the pool. My CH is already high (630) :shock: . Trichlor will not add calcium am I right? If i read it correctly it will add cya and lower ph which I want to do anyway? My ph is 7.5, trying to lower to 7.2 and TA is 90. Trying to stay low due to high CH. Please advise. Thanks again.
 

JasonLion

TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
37,880
Silver Spring, MD
You can certainly use a little trichlor, but you don't want to use too much. It won't take very long for trichlor to raise your CYA level higher than you want it to be.
 

evalm2010

Well-known member
Jun 21, 2010
56
Washington, DC
Thanks Jason. Maybe I can do half and half. On Thursday night I'll bump the FC to 15 using bleach then use a couple of trichlor tabs in the floater. I'll remove the floater as soon as I get back Monday evening. I've pretty much convinced myself this is what I'll do. If anyone else has any recommendation I'd really appreciate it. BTW, Jason thank you so much for creating the pool calculator. I have it on my iphone, it has a permanent icon on my ipad, and I have it bookmarked on my laptop and my computer at work. I can honestly say I'm a dependent. :goodjob:
 

Steve456

LifeTime Supporter
Jun 3, 2008
132
Texas
I would suspect organics in your pool. Your 24 hour Cl loss is greater for a indoor pool in DC than my loss of Cl for an outdoor pool in Texas. My CC is less than .5. My pool test water is normally clear after I test for CC.
 

evalm2010

Well-known member
Jun 21, 2010
56
Washington, DC
Thanks Steve. I kinda suspect that too. When I did an overnight FC loss test and only lost 1 ppm with <.5 CC, I thought I was done shocking. Being new to this, my 24 hour FC loss seemed normal (to me) without realizing mine is an indoor pool and is not exposed to sun like everyone else. Needless to say I am shocking again. :|
 

Isaac-1

TFP Expert
LifeTime Supporter
May 10, 2010
6,711
SW Louisiana
My indoor vinyl lined pool in Louisiana FC loss with no one swimming is around .5 ppm FC per day with 20 ppm CYA, it of course increases with heavier bather load. Being this low of loss and rounding error of the test, it is hard to say with precision, but this number is based on time to drop from shock level with light to no bather load.

Ike

p.s. your sky lights may make a difference depending on material they are made out of, standard glasss will block a high percentage of UV, where plastics like Lexan or plexi-glass may block much less (depending type, coatings, etc.). Also if you have a heater (even solar heat) FC consumption will be higher.
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,082
San Rafael, CA USA
The amount of chlorine loss for an indoor pool not exposed to sunlight and with minimal bather load varies by temperature, but is usually in the range of 0.5 to 1.0 ppm per day. So losing 3 ppm per day is certainly unusual. Unfortunately, shocking might not eliminate whatever is consuming the chlorine, but when shocking try and air out the pool as much as possible and you can even open up the skylights and windows to let sun hit the pool even though that will use more chlorine. UV helps to accelerate breakdown of slow-to-oxidize organics in the pool. Another option, at least for ongoing maintenance, is to use non-chlorine shock (MPS) though you'll need to get the Taylor K-2042 MPS interference remover since MPS will register as CC.
 

Isaac-1

TFP Expert
LifeTime Supporter
May 10, 2010
6,711
SW Louisiana
I have the Taylor MPS test and generally find that I don't use it much as all MPS (which tends to show as elevated CC on standard tests) will tend to disappear from my pool within a couple of days after use. (I shock with 6 pounds of MPS about every 6 weeks during swim season, and usually shock with chlorine only at the beginning and end of the season)

Ike
 

evalm2010

Well-known member
Jun 21, 2010
56
Washington, DC
Okay so it looks like today I only lost 1.5 ppm. My FC was 11 last night and tonight it was 9.5, CC <.5. I think i'm getting there. I brought it back up to 13.2 tonight by dumping another 182 oz bleach. I want it to be still at shock level when I get back from work tomorrow. And then I will bring it back up to 15 and use trichlor in preparation for my trip. I try to open the windows and doors when i'm home. Unfortunately, it's only when I get home from work until I go to bed and the occasional day off here and there. The skylights don't open unfortunately. :( I have to look into and study MPS. It took me a while to understand BBB but I think I'm starting to get the hang of it. I enjoy playing with the TF100 kit so I'm pretty sure I will like the Taylor K-2042. The only thing I don't like is the increasing cost of the maintenance of this pool.

Ike, are you saying you basically maintain your indoor pool by using MPS? How will i incorporate that with BBB? Do I start using it when I'm done shocking with chlorine? Thank you all for your input. Greatly appreciated.
 

Isaac-1

TFP Expert
LifeTime Supporter
May 10, 2010
6,711
SW Louisiana
I am currently using 5.25% bleach for the daily chlorine dosing (now automated with a metering pump), in general if/when I get above .5 ppm CC or about every 6 -8 weeks which ever comes first I does with 6 pounds of MPS and see if that greatly lowers/eliminates the CC. If not I then do a chlorine shock, and follow up with another round of MPS. If I have a problem with visibly cloudy water and on the way to a full algae bloom (like earlier this year when I had a broken return line then a dead pump motor so was without water circulation for over 2 weeks) I will skip straight to doing a Chlorine shock, hold at shock level as normal, then follow with MPS. I try to avoid shocking with chlorine as it takes over a week for the FC level to fall from shock level to ideal FC level after shocking.

Ike

p.s. I find it impossible to eliminate all CC with Chlorine shock alone
 

evalm2010

Well-known member
Jun 21, 2010
56
Washington, DC
Thanks Ike, I think I got it. I'm leaning towards trying this method. This question has probably been asked here many times but is there any negative impact of long term use of MPS? I promise I will read up on this as soon as I'm done posting. I am willing to try just about anything as I have been working on this pool for over 6 weeks now (thank God I discovered TFP two weeks ago). The previous pool caretaker used cal-hypo like there's no tomorrow. As a result my CH is at 630. I just don’t want to make the same mistake. We'll probably replace the filter and pump soon and will drain some of the water when the time comes but will the use of MPS affect anything else? Summer is halfway over and I haven't been into the pool. :(
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,082
San Rafael, CA USA
The only downside to using MPS is that it builds up sulfates in the water, but it's not clear as to what level this becomes a problem. High sulfate levels can be a problem for SWG systems and splash-out of water high in magnesium and sulfates can be harsher on porous stone surfaces. A sulfate level of 220 ppm lowers the saturation index by 0.1; 500 ppm by 0.2. Unfortunately, there isn't an inexpensive test for sulfates. Sulfates in the presence of higher salt levels (5000 ppm) can result in very rapid corrosion of stainless steel.

Indoor pools are a challenge in controlling CCs. Using a supplemental oxidizer, such as MPS, is helpful in this situation. Another alternative is to use a UV system or otherwise get UV from sunlight exposed to the pool for at least some period of time.
 

Other Threads of Interest