Muriatic Acid SNAFU?!?

Torqued · Jun 12, 2019

Hey guys, so i recently changed over to IO salt and as such felt the need to lower the DKH a bit. So i bought some muriatic acid and added it to my change water per instructions I've read here.

30gal x 2 ( dkh amount to drop) x .123 = 7.38ml.

So i added it and let aerated the water over night. I probably should have tested the dkh again before adding to the tank, but i didnt. After testing my tank dkh the next day i noticed the alk was up at least .75 dkh from normal, so obviously the acid i added did NOT drop the dkh to 8.0 as it should have.

Next day corals start looking worse, which is odd after a WC.....

So last night i made another batch of water...this time i tested the water before adding it. Ive already added 9ml and the dkh is still 9.0! Now i am wondering what the heck is going on. I think i may have some weak acid.....or perhaps worse, something not pure muriatic acid. I THINK my fear was true.....after looking closer i see it says "safer formula, 90% less fumes than standard muriatic acid". I suspect this stuff is NOT OK to use.....

Also looking at the data sheet it says its 20% hydrachloric acid....thats a pretty low concentration isnt it?

Can someone confirm/deny my suspicion?

Help Randy!

P-Dub · Jun 12, 2019

STOP adding anything to lower your dkH. 9.0 is a perfectly acceptable level for change water.

Torqued · Jun 12, 2019

P-Dub said:
STOP adding anything to lower your dkH. 9.0 is a perfectly acceptable level for change water.

I will respectfully disagree. I like to maintain my alk at 7.5 to 8.0. adding 30g of 9.0 water to my 200g system has a noticable rise. I suspect the water i added previously was closer to 9.75 and increased my tank alk by about .75, which i would like to avoid.

Steve Erekson · Jun 12, 2019

I believe the "90% less fumes" ones are the 20% HCl concentration instead of the commercial 30% and doesn't contain any extra additives or anything.

LobsterOfJustice · Jun 12, 2019

The “Green” low fume formula should just be more dilute - resulting in you needing to add more of it to achieve the same result (as you noted). It isn’t any less safe per se (ie doesn’t have additional chemical additives to make it low fume).

However, as this is an industrial chemical used for etching concrete, I doubt they are diluting it with RODI water. Personally, I don’t trust the quality control of either the green or standard versions, so I order lab/reagent grade sodium bisulfite and use that to lower my IO alk instead.

Sabellafella · Jun 12, 2019

Torqued said:
I will respectfully disagree. I like to maintain my alk at 7.5 to 8.0. adding 30g of 9.0 water to my 200g system has a noticable rise. I suspect the water i added previously was closer to 9.75 and increased my tank alk by about .75, which i would like to avoid.

What is your tank running at before all of the water changes?

Torqued · Jun 12, 2019

Hopefully you are both correct.....

I decided to play it safe and ordered the seachem acid buffer. It will do the job and is intended for tanks. It was only $11 for enough to last years so its worth the premium to make me feel better

Torqued · Jun 12, 2019

Sabellafella said:
What is your tank running at before all of the water changes?

I said it in the part u quoted. I run ~ 8.0, so my goal is to use WC water that closely matches my tank dkh.

Sabellafella · Jun 12, 2019

Let's say your tank is 200 g. Tank alkalinity levels are stable at 8 dkh. 30 gallons is about a 15% waterchange. Let's say your using instant ocean witch mixes up at 11dkh. That Is a 3 dkh spread between your salt mix, and your tanks current dkh. Your addition will add that 15% higher alkalinity to your water(after the waterchange). That's ruffly about a .4 dkh addition to your chemistry after a waterchange, imo is nothing really to worry about considering the +/- on a hobby grade test kit.

Witch salt mix are you using?

Sabellafella · Jun 12, 2019

I tryed the muriatic acid for a little bit, from time to time but the whole concept and everything about it just doesn't sit well with me. I'm in the same boat as you also with a 20% waterchange. Alk is at 7.5 and reef crystals is around 11.5. Something like a .8 dkh swing for me after a water change, and the corals never cared (I think) so I just continued on it.

Torqued · Jun 12, 2019

The problem is that small swing doesnt get corrected because i run a calcium reactor that keeps things pretty solid. Using water that makes a significant jump one way or the other, requires me to adjust the carx....which i dont like doing.

So here is the million dollar question....do i trash this WC water or do i use it

. Either way im done using the green stuff just in case

Sabellafella · Jun 12, 2019

Torqued said:
The problem is that small swing doesnt get corrected because i run a calcium reactor that keeps things pretty solid. Using water that makes a significant jump one way or the other, requires me to adjust the carx....which i dont like doing.

So here is the million dollar question....do i trash this WC water or do i use it . Either way im done using the green stuff just in case

Yea its ruff trying to find that balance. Takes alot of testing and time to get it all figured out. I'd still do the water changes, 15% isnt much. If your alk starts rising just go without the waterchange until the next time you feel its proper to do so. You'll always have coralline, corals and stuff attempting to butcher your alk, can use the water changes to correct the alk if it starts to drop.

TMB · Jun 12, 2019

1. If you really need to lower the Alk of your change water, you can muriatic acid from HD or a pool supply place (make sure of the ingredients)
2. I think there is a testing error in the result you stated, changing 15% with 10DKH water should only make a rise of ~.28 which should be totally acceptable. Here's a quote from Randy:
"FWIW, if your tank is at 9 dKH and you do a 10% change with 11 dKH water, the alk will only rise by 0.2 dKH, so I agree that smaller changes can reduce the bump and make it adequately small.

" (@Randy Holmes-Farley )
I know the numbers are slightly different but I think the calculation is correct.

To answer the original question, I would only use muriatic that had a label that stated the exact ingredients. So unless your's does, I would stop using it.

homer1475 · Jun 12, 2019

I also found the green stuff didn't do the trick, or I had to add way more then my calculations(found I had to add nearly twice as much as the standard calculation). I ended up buying 99.9% pure muriatic acid at my local ACE hardware. It's designed to be put in pools for the same reasons we are using it in our water. A gallon jug is like 25$ and lasts me nearly a year with 50G WC a month.

Torqued · Jun 12, 2019

homer1475 said:
I also found the green stuff didn't do the trick, or I had to add way more then my calculations(found I had to add nearly twice as much as the standard calculation). I ended up buying 99.9% pure muriatic acid at my local ACE hardware. It's designed to be put in pools for the same reasons we are using it in our water. A gallon jug is like 25$ and lasts me nearly a year with 50G WC a month.

This stuff also says its for pools, which is why i took the risk. Its probably ok, just far weaker.....i think im going to use this WC water. I takes nearly an entire bag of IO salt to mix up my water to 1.026 so i would prefer not trash it. Unfortunately the ph is now like 7.3 so ive gotta aerate it again overnight.

SeaDweller · Jun 12, 2019

Torqued said:
Hopefully you are both correct.....

I decided to play it safe and ordered the seachem acid buffer. It will do the job and is intended for tanks. It was only $11 for enough to last years so its worth the premium to make me feel better

I use this too.