Reverse Osmosis Water

[Jim Fritz]

I just got a new water purification system that gives me "whole house" soft water, and a "RO" faucet in the kitchen for drinking and cooking.

My question is: "Is Reverse Osmosis water OK for partial water changes or should I stay with the regular soft water, or continue to buy filtered water from the machine in front of the grocery store, which is what I have been using?
Same question for adding water for normal evaporation; (about 1/2 gallon per week.
Any other insight appreciated. Thanks.

 

[ZxC]

For water changes, you must remineralize RO water to yield gH and kH (only if you are not using a buffering substrate such as ADA soil, Stratum, Contra soil etc. etc.). If you are using a buffering substrate, there is no need to raise kH.

Simplest and cheapest, and likely the easiest way to do this is use these 3 compounds:

CaSO4 (Gypsum) - Can buy online for cheap, DIY beer brewing stores have good quality CaSO4. Also available at GLA
MgSO4 (Epsom Salt) - Can buy from local drug stores, or online. Make sure it is plain / no additives / non-scented. You want pure MgSO4. Also available at GLA.
KHCO3 - Can buy online, likely from home brewing suppliers again, this one is not available at GLA.

After that, all you need is a small jewelry scale with calibration weight and 0.001 gram accuracy. $10-$20 off amazon will get you one that will work well. Up to 50 grams is perfect.

Okay, next you'll want to head to https://rotalabutterfly.com/nutrient-calculator.php . Get to know this website. Punch in your water volume you change, select DIY, select your compound to dose (CaSO4.2H20 or MgSO4.7H20 or KHCO3) select dry dosing, select "dose to reach target" and then type in you target Ca level, Mg level and degrees of kH into the text box. Hit calculate and it will tell you how much to add into your water change water.

I recommend 30ppm Ca, 10ppm Mg and 1.0 degrees of kH.

This mix will yield you:

6-7 degrees gH
1 degree kH
pH of 7.1 - 7.2
and relatively low TDS

This mix is good for plants and fish and shrimp.

As to top-offs, use 100% no additives RO water. Only dose those compounds into your incoming water change water. Dissolve into the water first to avoid pH and TDS shock.

 

[earhtmother]

Not disagreeing with ZxC but......it all depend what your doing with your tank. For great plants he is DEFINITELY correct. If like me there are no living plants and you don't for some reason want to keep the water routine you have now then you CAN go RO only or 50/50. I'm on a qell & my shrimp tank is a 50/50 mix with NO mineralizing and the moss etc does just fine. In general straight RO is not a good idea

 

[BBradbury]

Hello Jim...

RO water is sterile. It has no minerals in it. Minerals help maintain a steady, healthy water chemistry and minerals guard against sudden changes in tank water. Fish and plants use the minerals in tap water for good health. This is one of the most important reasons for removing and replacing the tank water regularly. There are some tanks that use house plants as filtration and in these tanks, RO or distilled water is needed to maintain this type of tank. I would use strictly treated tap water in your fish tank.

B

 

[Jim Fritz]

Thanks, but that sounds like way too much work. I think I'll just stick to what I have been doing in the past as the fish seem to get along just fine that way.

 

[Jim Fritz]

Thanks. I have no living plants in the tank and what I have been doing is just fine for the fish. No use in adding a lot more work.

 

[ZxC]

Use it for top-offs then