How would RO water affect my tank?

10g
ph 7.8
gh 7
kh 5

I'm curious how RO water would affect my tank if it was half RO water. I'm assuming it would more than likely lower my ph and half my hardness..... Is this correct?

Is this a reliable way to lower my ph and hardness?

I want to add a betta to the tank. I know some already believe my water is safe for a betta. I personally don't believe that. If this method doesn't work, I won't be getting one. Thanks, everyone!

 

Water qualities such as hardness (GH) and alkalinity (KH....well, not exactly the same, but let's not complicate matters too much), reflect certain mineral concentrations or certain ion concentrations (depending on which level or perspective one likes to approach these water qualities).

Concentration = amount per water volume.

Hardness for instance is the amount of calcium and /or magnesium ions per volume.

For instance, your water can measure 35.7 mg/l calcium. Also expressed as 35.7 ppm. Or 35.7 GH.

This equals to the more familiar 5 dGH.

If one would mix the water containing 35.7 mg/l calcium with RO water, which has 0 mg/l calcium, in 50:50 ratio, the concentration of calcium will be half: 17.9 mg/l = 2.5 dGH.

The same rationale applies to KH, which in our hobby but also in natural bodies of water, is mostly determined by carbonates or bicarbonates. From tap water, most likely bicarbonates.

You can divide all your parameters by the ratio in which you mix tap water with RO water. I can further elaborate. Let me know if this helps already.

When people refer to hard water in the fish keeping hobby, they mostly refer to GH. When people refer to hard water in the planted tank hobby, they probably refer to KH.

Regarding pH. Do you have a moment? I would ignore it. In planted tanks, ignoring is standard. Sure, there are hardcore hobbyist that like to control everything. But pH is a beast in planted tanks.

If you have hard water (GH) and like to keep soft water fish, diluting your water with RO is great.

 

Water qualities such as hardness (GH) and alkalinity (KH....well, not exactly the same, but let's not complicate matters too much), reflect certain mineral concentrations or certain ion concentrations (depending on which level or perspective one likes to approach these water qualities).

Concentration = amount per water volume.

Hardness for instance is the amount of calcium and /or magnesium ions per volume.

For instance, your water can measure 35.7 mg/l calcium. Also expressed as 35.7 ppm. Or 35.7 GH.

This equals to the more familiar 5 dGH.

If one would mix the water containing 35.7 mg/l calcium with RO water, which has 0 mg/l calcium, the concentration of calcium will be half: 17.9 mg/l = 2.5 dGH.

The same rationale applies to KH, which in our hobby but also in natural bodies of water, is mostly determined by carbonates or bicarbonates. From tap water, most likely bicarbonates.

I can further elaborate. Let me know if this helps. You can divide all your parameters by the ratio in which you mix tap water with RO water.

When people refer to hard water in the fish keeping hobby, they mostly refer to GH. When people refer to hard water in the planted tank hobby, they probably refer to KH.

Thank you! That's what I thought. I appreciate it. Let me ask you this, if I choose an RO water source, do they usually maintain the same ph? I'm not going to end up with fluctuations am I? I know nothing is guaranteed. But in your experience, do they usually maintain the same ph? Also, why would I get RO water and not another distilled water?

 

RO water is neutral, 7 pH, but obviously contacts air once it is out of the RO system, upon which the pH drops due to absorbing CO2 in the air.

When you dilute the RO water with tap water, it depends on the amount of KH and also dissolved CO2 in your tap water.... what the pH will be... for the time being....

Really, I would forget pH. If your dKH is more than 1 you'll be fine. Because microbes in your tank eat carbonates (KH), a dKH of 3+ is fine. So focus on KH instead, provided you worry about pH fluctuations!

The KH keeps the pH stable.

 

RO water is neutral, 7 pH, but obviously contacts air once it is out of the RO system, upon which the pH drops due to absorbing CO2 in the air.

When you dilute the RO water with tap water, it depends on the amount of KH and also dissolved CO2 in your tap water.... what the pH will be... for the time being....

Really, I would forget pH. If your dKH is more than 1 you'll be fine. Because microbes in your tank eat carbonates (KH ....again, not totally equivalent), a dKH of 3+ is fine. So focus on KH instead, provided you worry about pH fluctuations!

The KH keeps the pH stable.

Thanks, I really appreciate it. I may go this route. We'll see.