A shocking question....

[anne]

This sort of relates to the other shocking thread, but I have a little puzzle: I generally add MPS about every other week. Sometimes I do it based on checking CC, and sometimes I just figure "well, it has been 2 weeks, it must be time."

A couple days ago I checked my CC with my Taylor kit, and it was just under 0.5 (estimating pinkness, here). It had been two weeks since shocking, so I planned to add MPS, then forgot to do so. This morning I checked the water after a soak......checked CC just for fun, assuming that I'd go out and add MPS- but the CC was zero. Really, no pink at all. I always add 1-1.5 tsp chlorine after every soak, having been using the tub about 2 out of 3 days lately. With no superchlorination, and no MPS, where'd the CC go??? Do I  add MPS "just because"? The water seems fine- pH has been steady at 7.4-7.6 for weeks. Only other thing I add weekly is "defender" and I have ozone.

[sledjunkie]

I would just shock every two weeks to be safe. It won’t hurt. Maybe sometimes you have enough combined chlorine after the two weeks, maybe sometimes you have barely any, but if you can get away with every two weeks that's pretty good. That way you can safely not worry about testing for combined chlorine anymore and just shock every two weeks.

A month ago I switched from shocking  MPS to shocking with Dichlor as I was sick of constantly balancing my PH every time I shocked with MPS. Do you have this problem too?

[Vinny]

anne,

To answer your question, if you had 0.3 PPM CC and you added 3 or more PPM you took care of the CC by have 10x FC of the CC. Although not a shock dose it was enough to get rid of the CC.

I find it interesting in the other shock post that you get 3 PPM with 1 teaspoon and a 400 gallon tub. I have a 400 gallon tub and I only get about 1.5 PPM from a heaping teaspoon.

[Vinny]

I would just shock every two weeks to be safe. It won’t hurt. Maybe sometimes you have enough combined chlorine after the two weeks, maybe sometimes you have barely any, but if you can get away with every two weeks that's pretty good. That way you can safely not worry about testing for combined chlorine anymore and just shock every two weeks.

A month ago I switched from shocking  MPS to shocking with Dichlor as I was sick of constantly balancing my PH every time I shocked with MPS. Do you have this problem too?

Actually if you use enough chlorine to get rid of the CC then you really never need to shock.

Take a look at your alkalinity reading  - whenever I use MPS I rarely need to adjust PH. This is an indication that your alkalinity is too low, this is the only time I worry about alkalinity. I can get 3 weeks or so using MPS to shock. I do use MPS sometime 2 times a week if I start to get a foam problem.

[pg_rider]

Are any of you people in the Colorado Springs area and, if so, would you be willing to take care of my water for me for a fee?  Just when I think I have a plan in mind I read these threads and feel like I'm never going to get it sorted out!!!

[sledjunkie]

I suppose Vinny is correct, you could be getting rid of the combined chlorine by adding more than necessary as your dosage, however I would just shock it every two weeks and not worry about testing for combined chlorine.
I think it's safe to say most (not all) people shock once a week, so once every two weeks is great.

Vinny - regarding your experience regarding your 1.5ppm vs  Anne's 3ppm using 1 tsp. Wouldn't this depend on what your PH reading is? I'm guessing yours is on the higher end and Anne's is on the lower.

[sledjunkie]

Oh, and my Alk reading is about 90 or 100, which is on the lower side I think.
What's your Alk Vinny? Thanks for the advice.

[Vinny]

I suppose Vinny is correct, you could be getting rid of the combined chlorine by adding more than necessary as your dosage, however I would just shock it every two weeks and not worry about testing for combined chlorine.
I think it's safe to say most (not all) people shock once a week, so once every two weeks is great.

Vinny - regarding your experience regarding your 1.5ppm vs  Anne's 3ppm using 1 tsp. Wouldn't this depend on what your PH reading is? I'm guessing yours is on the higher end and Anne's is on the lower.

No, the only thing that the PH affects is the amount of killing chlorine vs oxidizing chlorine but the PPM is determined by the volume of water. At a lower PH, you get more killing action and at a higher PH you get more oxidizing action.

Your tub should be about 350 or 400 gallons (I forget if its 7x7 or 8x8) and if you put in 1 teaspoon how much does that give you?

My ph is at 7.8 after adding baking soda and I let it drift down to 7.2 but it takes about 3 weeks for it to happen. Right now its at 7.6 and has been there for about 2 weeks and I think I've used MPS about 2 or 3 times since adjusting my PH. I tend not to worry about alkalinity since it rises and falls along with the PH as long as I use baking soda.

My alkalinity reading is about 60 to 110 depending on the PH. I am on my way out but I will check my PH and alkalinity and let you know the readings when I get back.

[anne]

anne,

To answer your question, if you had 0.3 PPM CC and you added 3 or more PPM you took care of the CC by have 10x FC of the CC. Although not a shock dose it was enough to get rid of the CC.

I find it interesting in the other shock post that you get 3 PPM with 1 teaspoon and a 400 gallon tub. I have a 400 gallon tub and I only get about 1.5 PPM from a heaping teaspoon.

I may have to verify this fact. This is how i remember it being, but since I almost always check my water values just as I'm getting out of the tub, before adding chlorine, it has been a while since I checked FC.

As far as using MPS and pH concerns, my water "likes" to go basic on me, so MPS seems to be good in my situation.

[sledjunkie]

Well... My PPM Chlorine reading is higher when my PH is on the lower side as opposed to when it's on the higher side.
This is what my theory was as to why Ann was getting higher PPM results, not how much killing vs. oxidizing it's actually doing.

[Vinny]

I got home a little later than anticipated but I will get you those figures tommorrow.

What do you use to test the chlorine?

[sledjunkie]

Drop based kit from walmart.

[tony]

Chlorine will oxidize.  Also, ozone will oxidize.

[Vinny]

Here's my numbers as of this morning:

PH 7.6 and alk 100 PPM

A funny thing is I shocked on Sat morning with 10 PPM and I still have a 1 PPM residue, I don't shock with dichlor that often so I was surprised to see a residue still ... talk about a complete bacteria kill!

[anne]

I really dont think that the level of pH can affect the free chlorine LEVEL, just the effectiveness of that chlorine. I have never seen or read any reference to such a relationship. Correlation doesnt imply causation, right?