Muriatic Acid.... yea or nay?

Scott07

New member
I'm going to be setting up a dosing pump this weekend for 2 part. I've been manually dosing 2 part up until now.
I use IO Reef Crystals which mixes up to somewhere around 10 or 11 dkh for my weekly water changes. I try to keep my tank at 8.5dkh, and test every single morning. I've been compensating for the higher alk in my WC water by only dosing about half of my normal 2 part dose on water change days, and letting the higher alk of the new water balance the rest for that day.

Rather than try to replicate what I've been doing with the dosing pumps...... can I start using muriatic acid in my water change water to achieve 8.5dkh.... and thereby leave the dosing pumps running on the same schedule onWC day?

Has anyone used muriatic acid and can confirm for me this is safe for my tank as long as I'm careful in my measurements?
 
I wouldn't think your water change is effecting your kh much unless you are changing more than 50% of the water volume. Maybe something like a .2 or .3 rise.
 
I wouldn't think your water change is effecting your kh much unless you are changing more than 50% of the water volume. Maybe something like a .2 or .3 rise.

I wouldn't have thought so either..... but i tested about a 1dkh difference yesterday before and after. 8.3 to 9 or so borderline scares me with all the sps I have. I'm changing about 16 gallons on a 65 or 70 total volume system weekly.

(70-16)×8.3 + (16 × 11)/70 = 8.91dkh

I'm just concerned full amt. dosing of 2 part on WC days will cause my alk to keep climbing week to week unless i adjust for it somehow.
 
Yes its very common to use muriatic acid to lower the alk of freshly mixed saltwater prior to adding it to the tank water..

In the future if you want just switch to a salt mix with a lower alk so you don't need to do that..

There is a formula floating around somewhere but..
If you use Muriatic Acid (approximately 33%-35% HCL) bought from a hardware store, you will need to use approximately 0.123 ml of the Muriatic Acid to reduce 1 gallon of salt mix 1 dKH.
 
Yes its very common to use muriatic acid to lower the alk of freshly mixed saltwater prior to adding it to the tank water..

In the future if you want just switch to a salt mix with a lower alk so you don't need to do that..

There is a formula floating around somewhere but..

Excellent, thank you! Ive considered switching salts many times..... but its one of the last few things i still buy from my LFS.... almost everything else is online now.
 
Mcgyvr is right. You can use it in your makeup water.

Just a reminder: HCl is a strong acid and is melt your skin kind of stuff. Wear some PPE, and never add it to a display.
 
I do it all the time with reef crystals. Just subtract current tank dkh from rc mix dkh. Multiply the difference times the number of gallons then multiply time .123.
 
Mcgyvr is right. You can use it in your makeup water.

Just a reminder: HCl is a strong acid and is melt your skin kind of stuff. Wear some PPE, and never add it to a display.

Thank you! Will do on the PPE. Am I right in assuming Hydrochloric acid works equally well, or is essentially the same thing, if that's what i can find?
 
Thank you! Will do on the PPE. Am I right in assuming Hydrochloric acid works equally well, or is essentially the same thing, if that's what i can find?

Same thing. Muriatic acid is designated for a specific strength of hydrochloric (33%).

Make sure to test the pH of your water before doing the water change. Smaller volumes should be ok within a few hours, but you need to give it time to gas off the co2. For example, I make up 45 gallons of water, add 15 mLs of concentrated HCL, and mix well (good surface agitation and complete volume turnover) for up to 2 days, or until pH comes up to around 8.

Also of note... I use reagent grade HCl when bringing alk down. The lower grade stuff could have heavy metals that may or may not affect your tank. Probably not an issue over a couple of water changes, but has the potential to have greater impacts if you always use it on your water changes. In the short run, use what you have to, but consider ordering better purity from a lab chemical company. Its a lot more expensive, but should last you quite a while.

SAFETY NOTE: I know other people have mentioned this, but goggles and gloves are a necessity. It won't instantly melt the flesh off you or anything, but, have fresh water nearby in case something bad happens. Also make sure you either have the kind that doesn't gas off as bad, or be sure to be in a well ventilated area. The vapors that come off of hydrochloric acid will definitely do respiratory damage. You'll know when you are in it, and generally you can see it as a white mist. I'd recommend measuring it outside and dilute it down with 3 times the volume of DI water then bring it to your salt water mixing container.
 
Same thing. Muriatic acid is designated for a specific strength of hydrochloric (33%).

Make sure to test the pH of your water before doing the water change. Smaller volumes should be ok within a few hours, but you need to give it time to gas off the co2. For example, I make up 45 gallons of water, add 15 mLs of concentrated HCL, and mix well (good surface agitation and complete volume turnover) for up to 2 days, or until pH comes up to around 8.

Also of note... I use reagent grade HCl when bringing alk down. The lower grade stuff could have heavy metals that may or may not affect your tank. Probably not an issue over a couple of water changes, but has the potential to have greater impacts if you always use it on your water changes. In the short run, use what you have to, but consider ordering better purity from a lab chemical company. Its a lot more expensive, but should last you quite a while.

SAFETY NOTE: I know other people have mentioned this, but goggles and gloves are a necessity. It won't instantly melt the flesh off you or anything, but, have fresh water nearby in case something bad happens. Also make sure you either have the kind that doesn't gas off as bad, or be sure to be in a well ventilated area. The vapors that come off of hydrochloric acid will definitely do respiratory damage. You'll know when you are in it, and generally you can see it as a white mist. I'd recommend measuring it outside and dilute it down with 3 times the volume of DI water then bring it to your salt water mixing container.

Really good information here, thank you! I was researching and having a difficult time determining if what i could get at home depot was good enough or not. I'm not super concerned about price, just want to do what's best for my tank, as it will be every WC. Do you have a link to where i can purchase lab grade hydrochloric? Am i going to get put on any sort of watch list if i purchase hydrochloric acid online lol?
 
I'm considering muriatic for the same purpose and had one additional question to the great info already posted, it's stored in a plastic container I assume it's safe to measure out using a plastic graduated cylinder?
 
Really good information here, thank you! I was researching and having a difficult time determining if what i could get at home depot was good enough or not. I'm not super concerned about price, just want to do what's best for my tank, as it will be every WC. Do you have a link to where i can purchase lab grade hydrochloric? Am i going to get put on any sort of watch list if i purchase hydrochloric acid online lol?

https://www.sciencecompany.com/Hydrochloric-Acid-Concentrated-500ml-P6505.aspx

They have different sizes available, but this is what I bought for water changes. Just for your info, lab grade is lower then reagent grade. That link is for ACS reagent which is a little better then just "reagent" grade.

Unless you are ordering it in bulk all the time, I think you will say off any meth cooking suspect lists... :)
 
I'm considering muriatic for the same purpose and had one additional question to the great info already posted, it's stored in a plastic container I assume it's safe to measure out using a plastic graduated cylinder?

Yes, plastic graduated cylinder is fine. Depending on the type, it may get brittle over time being exposed to the acid, but not in any amount of time you should be concerned about.

Its not going to dissolve on you or anything. :)
 
I agree with being careful with the muriatic acid. I'd also aerate and circulate the water for a bit after dosing, to allow the pH to rise.
 
Update

Update

I wanted to follow up with my results so far. I've just completed my second weekly water change using the hcl to bring down the alkalinity of my NSW. So far it's working as anticipated. The formula given by mcgyvr above has proven extremely accurate when using the 37% reagent grade hcl. When i test after dosing, the dkh I'm getting is almost exactly what the formula says it should be.

I've also noticed that a couple sps which used to slime a little bit with water changes now do not.... and PE remains good both through and immediately after my WC now.

So the plus side is clearly more stable parameters. And the negative is that now my water changes involve PPE and a couple additional tests besides salinity. Overall, I'm pleased with the results and this will be part of my WC routine moving forward. Thanks everyone for all of the information and help!
 
Been using professional strength muriatic acid from ACE hardware(31.45%HCL) for about 2 years now with no problems. Triton results do not show any signs of elevated metals of any kind. Just remember to let it mix well for a couple days to bring the PH back up.

Yes it's much easier to dose 2 part when your WC matches your DT(alk, Cal, and Mag).
 
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