Muriatic Acid Question

[Sumo1]

I was just checking a retail site for muriatic acid pricing and noticed the bottle label read "28%" hydrochloric acid. I think I remember Chem Geek stating that MA is 31% HCL from an earlier thread. My gut feeling is that this is a non-issue but would MA strength change calculations for pH adjustment?
Hal

[chem geek]

Hal,

31.45% is the standard traditional concentration and the one that most tables use (such as those in the Taylor kit). 28% is close enough since it's only about 11% weaker. It's usually better to use half the amount of acid and then recheck the pH just to be safe anyway, but if you wanted to calculate equivalent amounts you would just multiply the 31.45% calculated volume result by 1.12 when using the 28% acid -- not a big deal at all.

The bigger issue is for the roughly "half-strength" acid that is available at around 14-16% though at least there the calculation is simpler just doubling the required volume compared to the calculated 31.45% volume.

Richard

[steveinaz]

Richard you just answered my question. I thought I got another "weak" batch of muriatic acid from Home depot, but it's only 14%---that explains it. This acid, FWIW, is marked "for pools" on the box.

[aylad]

Just an FYI---I went to Lowe's earlier this week for muriatic acid and paid $6.98 for a gallon of 31%. Later in the day called the Tractor Supply store, and they sell a gallon of 31% for $4.98, but they also sell it in quart sizes, if you don't need that much. The stuff has gone up since I had to buy it last!!

Janet

[steveinaz]

The batch prior to this was from Lowes and it was definitely the 31% stuff. I thought muriatic was muriatic, had no idea it was sold in different concentrations.

Color me "schooled."

[mycalpool]

Hi Chem Geek

I was looking for a formula for muriatic dosage. Assuming Alkalinity, Hardness, CYA and Chlorine in normal ranges.

If you posted a thread with this info I would appreciate pointing me to it.

I was looking for something that would take
pool size in gallons
% concentration of muriatic acid
and lowering PH 0.2 ppm

[waterbear]

Hi Chem Geek

I was looking for a formula for muriatic dosage. Assuming Alkalinity, Hardness, CYA and Chlorine in normal ranges.

If you posted a thread with this info I would appreciate pointing me to it.

I was looking for something that would take
pool size in gallons
% concentration of muriatic acid
and lowering PH 0.2 ppm

TA also needs to be taken into account. That is why the only way to know how much acid will effect a particular pool is with an acid demand test. Otherwise you can use a ballpark figure of 1 pt /10k gallons as starting place, assuming TA is within normal range. IF TA is high then more might be required and vice versa.

[chem geek]

Hi Chem Geek

I was looking for a formula for muriatic dosage. Assuming Alkalinity, Hardness, CYA and Chlorine in normal ranges.

If you posted a thread with this info I would appreciate pointing me to it.

I was looking for something that would take
pool size in gallons
% concentration of muriatic acid
and lowering PH 0.2 ppm

You can use The Pool Calculator for some approximate computations including the effect of TA, but it's only approximate. My spreadsheet here will do the precise calculations, but it's not designed for novice users. You can PM me if you decide to use it and I can walk you through some sample calculations.

I intended to finish a simpler spreadsheet (that I've already started) that Jason could use for The Pool Calculator calculations and I took some stuff to Yosemite with me, but ended up hiking Half Dome instead. Some day I'll get around to it.

Richard

[poolaris]

Thanks for all the info. You have answered a question thats been bugging me for a while. I had been buying acid at Home Depot for about $8 and been using about 1 gallon a week. I recently bought some at a pool store for slightly less and my usage dropped to 1 gall every 2 weeks. I found an old Home Depot carton and sure enough the acid was half the strength - Wow! HD acid was also a yellow color whereas the new one is clear.