Remineralizing my RO water

[derek_686]

Question is in bold and underlined, the rest is explanation.
I just put in a 2 400gpd RO membrane system in my basement mainly to use for my tank top off and water changes but I also piped in three refrigerators and a few drink fillers throughout my house all ran off of a 30 gallon RO pressure tank. The 30 gallon tank was expensive but I thought it would be necessary to push the water from my basement up two levels and I also liked the idea of having water ready at all times to fill up a water change bucket. I can fill a 10 gallon bucket in under a minute and that refills in an hour!

The RO water tastes acidic to me now and I want to put a remineralization filter on it to improve the taste as well as I read it’s healthier to drink the more alkaline and mineralized water. There are several options but the ones I ordered say they increase ph and alkalinity and add calcium, magnesium, sodium and potassium. I am trying to decide if it is completely necessary not to remineralize the water for the aquarium.

I could only find a few discussions on this and the consensus seems to be not to remineralize aquarium water but I haven’t really read anything explaining why.
If I could remineralize the water right after the RO membrane (all water in pressure tank remineralized) then I would have great flow as all piping from pressure tank out is 1/2” at 33psi. Adding remineralization filters to only drinking lines reduces their pipe size, and flow, back down to 1/4” plus I would have to put multiple remineralization filters on for each drinking water line. I also read the lower ph might encourage things leeching from the pipes? I used 1/2 in pex b.

I realize this is a bit of an unusual system, but I wanted this to be a permanently installed, dual purpose system. Any discussion helping me understand the positives and negatives of using remineralized water would be helpful!

Aren’t minerals good for coral growth etc anyway? Are any of those particular minerals bad for anything? I understand using pure water gives you more control over what you add back in, but I don’t personally do a whole lot of advanced things w my aquarium. My aquarium philosophy is setting up an ecosystem that takes care of itself as much as possible.

Also, I realize I could tee off the RO to different pressure tanks but that is cost prohibitive if I want to maintain the pressure and flow throughout my house and have 10 gallons ready to go at any time for the aquarium. (Which is why I spent the money on the big tank)

 

[Naekuh]

No the salt mixes has all the minerals you need, so you don't need to remineralize anything like you do a freshwater shrimp tank.

Infact leave the water as pure as possible, and then mix it with the salt.

Don't put anything else in it, because if it has extra mag, you will oversaturate your water with Mg, which will then lead to all your Ca precipating out.

So no, you don't need to mix equalibirum or anything as again the salt mix you will use to get 1.026 will have all the minerals required.

 

[Randy Holmes-Farley]

I could only find a few discussions on this and the consensus seems to be not to remineralize aquarium water but I haven’t really read anything explaining why.

That is correct, it is undesirable.

Evaporation removes pure water, and that is what you should replace it with.

Seawater has a particular balance of every element. Adding a little more of some elements to "remineralize" it (which has no inherent value at all when put into seawater) will slowly cause that mixture to drift away from the natural balance of seawater.

 

[derek_686]

I don’t dose anything. Don’t a lot of reefers add mg and calcium etc to their water anyway to replace what is used up by corals though? I understand your answers and I agree that it is probably best to just add pure water but, being a big convenience in my setup, do you think it would truly be harmful over time? My understanding is the remineralization filter for drinking water would just add small trace amounts of those minerals (only raised it a few tds from what I’ve read)
And I honestly haven’t done a water change since I set up the aquarium. (Was hoping this setup would make it more convenient so I might actually do one) So my frogspawns could probably use a little extra ca haha. I guess I’m just wondering for someone like me who doesn’t do regular water changes to replenish minerals do you see any problem with adding trace amounts in with my top off water?
Is the sodium or potassium inherently harmful or anything, or are they desirable in the right amounts as well?
I appreciate the info!!

 

[Devisissy]

Using a system designed for home use versus reef use is folly. It's a personal pet peeve of mine. It's a basic reef necessity that people immediately try to cut the cost on, or cut corners. They won't spend $300-$500 on a RODI set up that will last a lifetime but will gladly spend that on a light or pump that will last only a few years. Get a unit or set up for the reef and a separate one for the home.

 

[Randy Holmes-Farley]

I don’t dose anything. Don’t a lot of reefers add mg and calcium etc to their water anyway to replace what is used up by corals though? I understand your answers and I agree that it is probably best to just add pure water but, being a big convenience in my setup, do you think it would truly be harmful over time? My understanding is the remineralization filter for drinking water would just add small trace amounts of those minerals (only raised it a few tds from what I’ve read)
And I honestly haven’t done a water change since I set up the aquarium. (Was hoping this setup would make it more convenient so I might actually do one) So my frogspawns could probably use a little extra ca haha. I guess I’m just wondering for someone like me who doesn’t do regular water changes to replenish minerals do you see any problem with adding trace amounts in with my top off water?
Is the sodium or potassium inherently harmful or anything, or are they desirable in the right amounts as well?
I appreciate the info!!

It is certainly possible and frequently done to use replacement of evaporated water to deliver a controlled amount of something, most often calcium hydroxide to add calcium and alkalinity. I did that for 20 years as my sole source of calcium and alkalinity (aside from water changes)

That would not be called remineralizing the water, and adding a random small amount of something that you have no reason to think you need is not a good plan.

Let's look at a commercial product:

Seachem - Replenish

www.seachem.com

Ingredients: calcium chloride, magnesium chloride, sodium chloride, potassium chloride

The amounts of each are low, but regardless, if you do not know you need them, there's no reason to spend time and money to add them, and even if you did need need them, this is not how I recommend doing so.

 

[Randy Holmes-Farley]

guess I’m just wondering for someone like me who doesn’t do regular water changes to replenish minerals do you see any problem with adding trace amounts in with my top off water?

Yes, that's exactly what I said: it is undesirable.

This is worth a read:

The Many Methods for Supplementing Calcium and Alkalinity - REEFEDITION

There is no aspect of reef aquarium chemistry more important than calcium and alkalinity. Many of my previous articles have described various aspects of these systems in detail. In reading those articles, aquarists will note one pervasive theme: that maintaining appropriate levels of each are...

www.reefedition.com

 

[derek_686]

Thanks for your time and info Randy!

It sounds like there is nothing wrong with the minerals themselves being back in the water, the issue is not being able to know or control how much of each is in the water.

Let me know if that summary seems incorrect.

 

[Randy Holmes-Farley]

Thanks for your time and info Randy!

It sounds like there is nothing wrong with the minerals themselves being back in the water, the issue is not being able to know or control how much of each is in the water.

Let me know if that summary seems incorrect.

Yes, that is largely true. All of the chemicals in the Seachem product, for example, are present in seawater in substantial concentration already, and may or may not be deficient (or elevated).