Acidic ro/di water

Scrandrew

New member
I will soon be setting up a 210 reef tank. This will be my first tank that I will fill using "well" water as opposed to city tap water. I assumed that the water would be very basic, based upon my incorrect assumption that dissolved minerals would somehow rise with the water. Instead, I assumed based upon acid rain, I found that the pH of my water was in the 6.4 range.

Accordingly, I was wondering what I should do to treat the water prior to mixing it with salt. Please tell me, if you would be so kind, the tyoe of product to use, if any, and any brand names that you may have experience with.

Thank you.

A~
 

Bonebrake

New member
RO/DI water when exposed to air for a day or so, has a pH of ~5.6 due to dissolved carbon dioxide gas in the water forming carbonic acid. To get neutral RO/DI water with a pH of 7.0 you have to boil off all of the dissolved carbon dioxide first.

I don't think that adding salt to acidic water would cause a problem, but if you want it to be less acidic you could add some baking soda prior to adding the salt.

What is the TDS of your well water?
 

Bonebrake

New member
If you're planning on using plan well water for a reef tank check the TDS first. If it is anything over 20 ppm I would not even consider it a possibility and purchase a RO/DI unit. You can buy a decent TDS meter for $20 on eBay shipped and a multi-stage RO/DI unit for under $200 shipped.
 

Scrandrew

New member
I have a kent ro/di unit with silica remover. It is supposed to be pretty good. After I run the water through the unit, what do I need to do, to bring up the acidic pH, if anything?

A~
 

Bonebrake

New member
I don't honestly think you need to do anything. I have heard people discuss buffering RO/DI before adding salt, but I don't remember the reasoning behind it and if it was necessary I would have made it common practice.

I don't add anything to my RO/DI prior to mixing, just add the salt very slowly, as soon as the water turns cloudy, I stop until it is clear again and add more until there is no salt left. I then let it mix with high flow for at least 48 hours and then use it immediately. I have been a very successful reefkeeper by this method for nearly two years now.

I do know three rules on mixing salt that should not be broken:

Use the purest water available: RO/DI or water with the lowest TDS possible.

Always add salt slowly to water and let it dissolve before adding more; never add water to salt.

Always mix salt for at least 24 hours and test it before adding it to your tank.

:)
 

bertoni

Premium Member
The pH of RO-DI water isn't measureable using hobbyist equipment, and the value isn't important, in any case, since RO-DI has no buffering. It'll conform to the pH set by the salt mix and ambient air.

A TDS meter is very useful to have when using RO-DI, since it'll tell you when various cartridges are shot.
 
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