Muriatic acid distribution methods

[dawndenise]

I saw something on another pool site (NOT known for its water balancing advice) that adding MA in a single stream in the deep end would lower pH and alkalinity but that dribbling it around the pool would only lower pH and not have much of an effect on alkalinity.

This didn't sound right to me, but thought I'd put it out here to get the water-balancing experts' opinions. If somehow it IS true, well, then I'll definitely be changing my distribution method!

[Phillbo]

I broadcast mine while walking around the edge of the pool but I did hear a guy at the pool store explaining to a customer how to add it in 4 areas of the pool only. I'm not sure if he was trying to drive down his Alk or not .. I'll let the experts here inform us on the validity of this method.

I'm curious as well.

[doggie]

I was told that adding it around the perimeter of the pool would lower PH more than if you added it to one single spot in the deep end.

[JohnT]

All are bad ways to add it and all are wrong with regards to the effect it has on the TA and pH. Muriatic acid lowers both pH and alkalinty regardless of how you add it. It is much heavier than water and sinks straight to the bottom and stays there unless you run the filter when adding it. Even then, you should take precautions to make sure it gets mixed in with plenty of water by either adding it very slowly in front of a return or mixing it with water before adding it to the pool.

[Spensar]

All are bad ways to add it and all are wrong with regards to the effect it has on the TA and pH. Muriatic acid lowers both pH and alkalinty regardless of how you add it. It is much heavier than water and sinks straight to the bottom and stays there unless you run the filter when adding it. Even then, you should take precautions to make sure it gets mixed in with plenty of water by either adding it very slowly in front of a return or mixing it with water before adding it to the pool.

I had added the crystal/powder form and realized a couple of minutes later that my pump was off... never seen me move so fast.... I brushed the bottom to be sure it was well stirred too.

[cschnurr]

I believe the Taylor Test Kit user manuals refer to a 'slug' method of adding acid which is supposed to affect TA more than pH. However this has been debunked elsewhere on the site.

[salinda]

I put mine in a single stream in front of the deep end return with the pump on. I add acid on a regular basis and I watch the plume to make sure it is hitting the return jet and mixing in. For me, that is a little to the side of the jet....

[waterbear]

Here (http://www.poolforum.com/pf2/showthread.php?t=7588) is the thread that talks about the 'slug method' and here (http://www.poolhelp.com/JSPSI_V1N2_16-30_AcidColumn.pdf) is a link to the paper that debunks it!

[aquarium]

I pour it in front of the deep end return with the pump running.

[Phillbo]

Gargle , rinse , swish and spit...... :D

[Sumo1]

Phillbo, I thought your teeth looked unusually bright:D
Hal

[davebva]

Speaking of distribution methods, has anyone seen or heard of this....

http://www.aquaservicedist.com/SMART-PH-KIT-WITH-FREE-SHIPPING-p-16866.html

If this thing really works and does not damage anything where the Acid enters the pool, then I'm sold. Talk about a maintenence free pool!! :D Just about the only thing I have to to most of the summer is add acid to keep ph in check

[waterbear]

Controllers with electrodes and automatic dosing wiith peristaltic pumps has been used on cmmercial pools for years. In fact, the Pool Pilot Total Control system includes such equipment. The main disadvantage is the price. If you have the extra $1500 lying around to install it and have the money for maintenance to keep it running properly then go for it.

[chem geek]

Also keep in mind that the website is incorrect in stating that the source of the rising pH from chlorine generators is from the basic/alkaline chlorine generation. As we know, the usage of chlorine is acidic and exactly compensates for the initial basic/alkaline nature of chlorine production so the net result is pH neutral (this post (http://www.poolforum.com/pf2/showpost.php?p=27573&postcount=12) describes the chemistry).

Since the true cause of pH rise in pools with chlorine generators is the hydrogen gas bubbles that aerate the water pulling out carbon dioxide that then gets outgassed into the air, the use of this automatic acid dosing product will result in a reduction in Total Alkalinity (TA) over time (just as periodic manual acid addition would). That's probably less of a hassle as the TA drops relatively slowly, but it is something to test periodically and adjust.

Richard

[ageorge]

Please pardon if I missed this elsewhere on the site (I searched on CO2 and found nothing, and search on "dioxide" got more hits than I could read), but speaking of adding acid--what about adding CO2 directly?

I'm guessing that is what the Pilot product does, and I know Hayward/Goldline has a product that does it--as a +/- $300 add on to a +/- $800 add on to a premium priced SWG. I just saw an automatic unit for about $1300. But I'm wondering if it couldn't be done cheaply with a tank and a hose...

I'm adding a SWG to a pool where city water is alkaline, and I'm running a fountain regularly to keep down high water temperature. We accidentally overfilled the pool a couple times this year, and after 3 gallons of muriatic my TA was 240. (I'm still adding acid...) I'm concerned about my acid bill for the rest of the season.

Is there any reason I can't just bubble CO2 into the pool? Any estimate on how much? Anybody tried it?

Andy

[chem geek]

Welcome to the PoolForum! :)

Injecting CO2 into the water will lower the pH with no change in TA, but if the cause of pH rise is due to carbon dioxide outgassing the far better way to handle that is to substantially lower the TA level in the pool since that is the primary source of this rising pH. These systems aren't cheap, but you could price them out.

SWG pools also rise in pH due to other factors that may include outgassing of undissolved chlorine gas. The only way to resolve this, other than using longer pipe runs between the SWG and pool and to point the returns downward (but that is worse for surface circulation), is to turn down the SWG on-time. That basically means you need to reduce the chlorine demand in the pool and there are two ways to do that. First, is to have a higher CYA level closer to 80 ppm, but have a corresponding FC level of at least 4 ppm (Ben's Best Guess CYA chart (http://www.poolforum.com/pf2/showthread.php?t=365) says 5 ppm FC minimum) since that will reduce the chlorine loss from the UV in sunlight (if you don't have a mostly opaque pool cover). Second, is to add 50 ppm Borates to the pool which are a mild algaecide as well as a pH buffer so can reduce chlorine demand from nascent algae growth.

There are many people with SWG pools that have significantly reduced the amount of acid they need to add -- some have even gotten to pH stability. They have lower TA, higher CYA, use 50 ppm Borates, and generally don't worry if the pH settles in at 7.7 instead of 7.5.

Richard

[salinda]

CO2 gas injection is used commercially and there are some residential systems available. Here is one of them:
http://www.poolsmith.com/
If you look at the FAQ's, you will get a lot of good info. It is sold to be used for pH control, and it appears that it actually doesn't control TA very much. In fact, they recommend that you use the system in a pool that has TA less than 160 for their system to be effective.

[ageorge]

Thanks!

Since bubbling CO2 won't affect TA, using CO2 wouldn't solve my current problem of high TA (which I agree is the main problem with my pH at this point). Nor would it prevent TA rise from my alkaline city water. :( The only time my pH stayed balanced was when I was using trichlor granular (was cheap at Walmart couple years ago).

CO2 would compensate for the CO2 loss from SWG and, if I'm understanding correctly, from the fountain. I don't know yet how much of a problem they will be, but I am anticipating a problem based on reading some of your other posts. I appreciate the review on using CYA to minimize the SWG operation.

Some of the other methods of reducing CO2 out gassing are new to me. I assume the point of longer pipe runs and/or pointing the returns down is to give the bubbled gasses more opportunity to redisolve. I have about 15-20 feet of pipe to my closest return--but the return is a fountain...

As you say, CO2 systems are not cheap. You may have talked me out of needing one anyway, but what I was wondering was whether I could just get a tank, a regulator and a hose and bubble it myself. A setup designed for beer making looks like it would be about $100. I'm wondering how much acid that would make.

Andy

[chem geek]

If you use the procedure to lower the TA substantially, then your rate of pH rise will drop a lot as well. Read the HowTo on Lowering Your Alkalinity (http://www.poolforum.com/pf2/showthread.php?t=191). There is no avoiding the amount of acid you need to add to lower the TA. You can use the "Effect of adding chemicals" section near the bottom of The Pool Calculator (http://www.thepoolcalculator.com/) to calculate how much acid it will ultimately take to lower the TA, though this isn't added all at once (i.e. follow the HowTo procedure).

It takes around 25-1/2 fluid ounces of full-strength Muriatic Acid (31.45% Hydrochloric acid) to lower the TA by 10 ppm in 10,000 gallons.

[PBLsQuad450]

I have checked out CO2 before. No real access for me to reasonable size tanks. Beer making? I think they were like 6lb. tanks or something odd. You need much more. Much, much more in your case specifically. Just a maintenance thing and you will need 2 20lb. tanks minimum, the 2nd so you can change out and re-fill etc.. With trying to lower your alk I would think these little jobs are just too small a tank, at least from I have read. OBTW, I live in Jersey. If I can't get large scale containers of compressed gas, toxic liquids or solids or other major corrosives and the like, I would think no one else can, because we manufacture so darn much of it right here in the garden state. Just my .02 anyway.

[ageorge]

Thanks, and thanks again. :)

Looks like I'll need to buy about 6 more gallons of muriatic for the TA problem. Hopefully I can keep the pH rise problem to a minimum once that is solved...

Andy