Adding muriatic acid with no returns

[AZPoolDad]

I don't have returns (in wall). My pump return system goes completely through the in-floor cleaning system pop ups. So what is the best way to add muriatic acid in this situation? For bleach I generally just pour very slowly around perimeter of the pool, with pump running of course.

 

[Melt In The Sun]

I just look to see.which popups are up, then dump a bunch there. It mixes very quickly so I don't worry about trickling it.

 

[AZPoolDad]

The bigger issue is that my PH is still at 7.8 this morning, after it being 7.8 yesterday afternoon. The pump was running all night so it is not a matter of poor mixing. My jug of acid that I used was old, probably a year old, but I put in a half gallon (yes, I know, too much . . . I got carried away). I can understand old muriatic acid losing its punch but not becoming completely useless. I have a 12,000 gallon pool and PoolCalulator.com tells me the pH should have come way down 7.0 or so, depending on the strength of the acid.

Could the acid have become completely useless sitting on the shelf in my shed? I live in Phoenix, AZ so it gets hot in the shed. It was Paddock Pools brand muriatic acid. I was shooting for a lower PH reading to bring my CSI into a more acceptable balance range. (And yes I know I need to drain about 75 percent of my water.)

I use a Taylor K-2006, and my current readings:

TC - 9.5
FC - 9.5
CC - 0.0
TA - 110
CH - 800
PH - 7.8
CYA - 150

 

[Melt In The Sun]

Nope, it doesn't go bad. Your pH probably started much higher (off the scale) and...is still likely off the scale. If you keep adding acid, it will come down.

 

[AZPoolDad]

Thanks for the reply, Melt. I was pretty sure it didn't go bad. However, if the Taylor kit's pH comparator goes up to 8.0, and over the past two months I've held a steady pH between 7.6 and 7.8 (never higher), how can it be "off the scale?" Wouldn't off the scale be a color tint of 8.0 or even a deeper red? I understand my chlorine is on the high side (purposefully so because of my CYA), but I would think if it was skewed, it would be consistently skewed.

I've just had such crystal clear water since going BBB a few months ago, I don't want to break what isn't broken.

 

[chem geek]

After you add the Muriatic Acid in an area, I'd just lightly brush that area to ensure thorough mixing, just to be on the safe side. It's true that with water flowing out from pop-ups, the risk for concentrated acid pooling is low.

 

[Richard320]

I'll bet you lowered TA by acid and raised pH by aeration with the pump running all night long! :lol:

If you want it mixed quick, pour the acid in, then jump in and start thrashing around in the pool, sweep armloads of water towards the area where it was added. The stuff is really soluble.

 

[JamesW]

Some of the acid might have been used up dissolving scale.

 

[AZPoolDad]

I think I just need to stop stalling the inevitable and do my 70 percent drain and refill. I was going to do a siphon from the shallow end stair area with a simultaneous hose fill on the opposite deep end. But I did the math, and at a 2 GPM siphon/fill rate, it would take 80 hours or more, and I'm not sure I want to be doing it for four straight days. Maybe it's time to rent a pump from Home Depot and just get it done over the weekend. Temperatures will be around 102 and I have PebbleTec which should be okay.

 

[Melt In The Sun]

Odd that it seems stuck at 7.8...very common to see it stuck at 8. Anyway, you'll probably make your life easier just by doing the drain and refill like you said. Rather than renting a pump, I'd would either:
- buy a pump (since you'll be using it every 2-3 years), or,
- do a little bit of replumbing on your pad so you can pump directly to waste.

I put a T above the pump with a 2" plastic ball valve and threaded cap on that side, so next time I need to drain I can just hook up a backwash hose and be done in a couple hours.