Reverse Osmosis Water Help Pls

Hey everyone, I'm in the process of starting to use RO water for a new 16 gallon tank I plan on buying. But I don't know how RO water works. I get people use RO water to get low pH or for soft water but how do people lower down the pH and or soften the water? Isn't the pH of RO 7.0 which isn't soft? How does it work?

 

It depends. Some RO doesn’t remove many dissolved solids. Now if you buy an RO/DI, that deionizes the water and removes nearly any dissolved solid. You’ll want to test not only the PH of your RO system, but you GH (general hardness) and KH (carbonate hardness). Is there something wrong with your tap water?

 

It depends. Some RO doesn’t remove many dissolved solids. Now if you buy an RO/DI, that deionizes the water and removes nearly any dissolved solid. You’ll want to test not only the PH of your RO system, but you GH (general hardness) and KH (carbonate hardness).

I do have a GH and KH test kit on hand (thank goodness).
Essentially, I plan on keeping a fish that requires soft water, and with that being said I need to use RO.
Is RO water already soft? How do I lower down the pH and keep it stable?

 

What kind of fish? Regular RO water isn't always soft and acidic, however, RO/DI water is always soft and acidic. For my Rams, I mix 3 gallons of RO/DI water with 2 gallons of tap water. This makes the water where I want it, but it might be different for you because we have different tap water.

 

What kind of fish? Regular RO water isn't always soft and acidic, however, RO/DI water is always soft and acidic. For my Rams, I mix 3 gallons of RO/DI water with 2 gallons of tap water. This makes the water where I want it, but it might be different for you because we have different tap water.

OH so there is a difference between RO and RO/DI?
I plan on keeping Black Darter Tetras.

 

There is yes. Ionization basically removes everything your reverse osmosis misses. Neither are good to drink yourself however, you need minerals. I really wouldn’t worry about your Tetras. What does your tap test like?

 

There is yes. Ionization basically removes everything your reverse osmosis misses. Neither are good to drink yourself however, you need minerals. I really wouldn’t worry about your Tetras. What does your tap test like?

My tap tests are
Ph: 7.6 or 7.8
GH: 11
KH: 7
These tetras need really soft water however, and aren't adaptable whatsoever since they're wild caught and real sensitive

 

Oh okay, yeah I didn’t think they were wild. Which I’d recommend an RO/DI, not just RO. Your tap is the same as mine, however, you have to mix it with your RO/DI with tap because the RO/DI will have 0 KH AND 0GH, which means it technically has no PH.

 

Oh okay, yeah I didn’t think they were wild. Which I’d recommend an RO/DI, not just RO.

Yes the water will be from an RO/DI unit.
How will I be able to maintain the right ph and trace elements if the water is stripped of minerals and what not? And since the fish I need require a low pH how do I accomplish that while keeping it stable as well?

 

Edited my last post. Additionally, when you’re topping off the tank you need to use RO/DI water. You need to play around with mixing tap with RO/DI until you get it right (in a bucket). I found that 3 gallons of RO/DI mixed with 2 gallons of tap got my water where I wanted it. Every water CHANGE requires this exact mix.

 

Edited my last post. Additionally, when you’re topping off the tank you need to use RO/DI water. You need to play around with mixing tap with RO/DI until you get it right (in a bucket). I found that 3 gallons of RO/DI mixed with 2 gallons of tap got my water where I wanted it. Every water CHANGE requires this exact mix.

Ok so this what I learned from reading about RO/DI water.
Basically when you use this type of water you need to raise the KH a bit so there is no pH swings, and GH bc fish need some minerals. Is that correct? And I can do that by either mixing the RO/DI water with tap or by using products such as Seachem equilibrium?

 

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Oh okay, yeah I didn’t think they were wild. Which I’d recommend an RO/DI, not just RO. Your tap is the same as mine, however, you have to mix it with your RO/DI with tap because the RO/DI will have 0 KH AND 0GH, which means it technically has no PH.

0 KH and 0 GH with deionized RO unit water does not mean it has technically no pH. It more than likely has a pH of 7 depending on the micron size of the RO unit membrane. Neutral pH is not no pH.

 

NavyChief20 since I want a lower pH than 7 how would accomplish that but also raising the KH enough that the pH won't be unstable?

 

NavyChief20 since I want a lower pH than 7 how would accomplish that but also raising the KH enough that the pH won't be unstable?

You're asking how to lower pH below 7 while raising KH (which actually absorbs acidity and is directly related to alkalynity) ? That's wicked hard to do. An increase of KH will absorb the acidity inyour water and bring it closer to 7 or above.

 

My RO/DI unit makes the water come out as 0 kh, 0 gh, and I don’t know the exact PH, but it’s definitely 6 or below. Also, I like to say no PH when I’m talking about fish because when the KH is 0, the PH just bounces around.

 

RO unit water by design will be between 5-7 pH units. It really is purely dependant on 3 micron or 5 micron and how many passes and what pressure between passes. If you have a resin column after the RO unit product discharge then you will deionize it. Resin columns are also known as an ion exchanger.

 

I actually measured the pH of freshly made RO water. It was 7 for few seconds. It went down as I was swirling the vial. Without a KH to buffer it, CO2 from the air combined with water to make Carbonic acid. Try it!

 

I actually measured the pH of freshly made RO water. It was 7 for few seconds. It went down as I was swirling the vial. Without a KH to buffer it, CO2 from the air combined with water to make Carbonic acid. Try it!

yep chemistry is fun

 

So can I just Seachem Equilibrium to raise the GH of the RO to the numbers I want and use Seachem Alkaline Buffer to raise the KH to the numbers I want AND then use seachem acid buffer to then lower the pH to what I want it to be? Or would it just be easier to use botanicals and or peat in a filter to then lower down the pH?

 

You can try the chemical approach, however it can be a struggle. You will most likely be chasing pH and have kH issues as well. The natural approach is slower but in the end it is better.

 

I would use Equilibrium to raise GH where you want it. Very good for plants, too.
As for lowering the pH, I would do the natural approach: driftwood, peat, Almond leaves.
Some people use strong acids such as Muriatic acid (Hydrochloric acid) to get to a certain pH. I don't recommend it especially if you have rocks or other decorations that might dissolve under such a strong acid.

 

Ok so I’ve come up with a plan, that might possibly work.
I’m going to use equilibrium to raise the GH
then I will be using baking soda to raise KH
and for the pH I’m just going to use botanicals and peat