my solution to lowering Total Alkalinity

[idowatsu]

My pool is fairly automated and indoor so maintenance sometimes gets neglected. I did a
cartilage filter cleaning, screen cleaning and have a unique solution for lowering the total Alkalinity. I add Muratic acid to drop PH to 7.0, luckily I have a digital PH read on my Chemtrol, then I have a shop vac dedicated for this task that I stick in the ladder to bubble the pool. I need to leave at least one door open for the gas to escape. This process takes about 24 hours to get to the recommended 60-80 range, I get up periodically is add acid throughout the night.
Thanks to the borates my algae problems are a thing of the past as well as the ph fluctuations. Thanks TFP[attachment=0:1hk41zsg]HPIM0960.JPG[/attachment:1hk41zsg]
This is a pic when new, the paint has faded and there is rust staining from the ladder now. Having shocked with bleach in the past, the liner has faded, what is the recommended amount to safely shock a vinyl pool ?

 

[chem geek]

The normal shock level is an FC that is around 40% of the CYA level as shown in the Chlorine / CYA Chart. However, any bleaching of your vinyl is more likely caused by having concentrated chemical pool where you add it (especially if such fading is uneven in the pool). You should add any concentrated chemical, including bleach or acid, slowly over a return flow with the pump running and you want to lightly brush the side and bottom of the pool where you've added it to ensure thorough mixing. However, if you properly maintain at least the minimum FC/CYA level, then you should hardly every have to shock the pool.

 

[idowatsu]

This is an indoor pool, the CYA level is between 0 and 10 and it works at that level, I have had problems in the past with the CYA above 50 interfering with the ORP reading on the chemtrol. my chlorine levels stay fairly stable. My drop test yesterday placed the CC>.5 for a TC @ 1.7 this is a little low because I just gassed off the pool to TA of 70 from 180, taking some chlorine with it. today FC is at 2, PH 7.5
I don't shock except when I leave for an extended period and the pump has been off.
the bleaching was from shocking at 12 when the CYA level was 60 the chlorine level stayed around 12 for several days, how does that come down sooner?

 

[chem geek]

the bleaching was from shocking at 12 when the CYA level was 60 the chlorine level stayed around 12 for several days, how does that come down sooner?

You can always use a dechlorinating agent such as sodium thiosulfate or hydrogen peroxide if you want to bring down the chlorine level. 3% hydrogen peroxide is equivalent in volume to 6% bleach in terms of what it dechlorinates (i.e. look up the amount of 6% bleach for an equivalent FC amount and use that same volume of 3% hydrogen peroxide to lower by that FC amount).

Well, that's very strange to bleach the vinyl with an FC of 12 and CYA of 60 for several days. I don't believe we've ever seen that before and we've had plenty of people shocking in their vinyl pools (mostly people first coming to the forum treating algae problems before they've converted to BBB). So I don't have an explanation for it unless the vinyl coloring was very weak so that even low active chlorine levels would react with it. 12 ppm FC with 60 ppm CYA is only equivalent to around 0.2 ppm FC with no CYA which is very low. Was the fading everywhere at and below the water line or was it uneven mostly in the area where the chlorine was added?

 

[idowatsu]

The fading was before I went to the BBB, it is even at the water line but the bottom has faded unevenly,probably concentrated borate when I added it, now it's mostly white/light blue with rust marks. I have spots this past year where the sand around the edges has pitted and left craters in the berm around the edge, at a loss as to what that might be, it is back filled about 18 inches above the bottom. I layed 1" vibrum horse mats as the floor of the pool for an even surface for Watsu, so I don't think it's seeping out the boards at the bottom. I am hoping they aren't pinholes in the liner settling the sand. I'll try to get a pic of them to post. this liner is 6 years old with a 20 year warranty but I'm sure they will tell me that I abused it . Hoping it lasts at least 10 years. It's a smooth lay job except around the in feed where the 96 degree water has caused some warping.