# Should you buffer RO water?



## xWingman48 (Apr 8, 2008)

Hey All,

My water out of the tap is pretty well liquid rock. pH 8.8, GH 22, KH 22. I realize that there is no sane way to make that water hospitable for software cichlids like apistos, so I got an RO unit.

Now I'm wondering what I should do as a starting "recipe". I see folks on here mixing in tap water with RO, but that will still give me a really high pH. Out of the RO unit, I have a pH of ~8 (not very stable), GH and KH under 2.

I feel like I need to add something to have a stable pH, and I'd like to have a KH at or above 3 if I can. What do you all recommend? Chemical buffer? Tap water mix? Let me know what you think.

Thanks.


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## BelieveInBlue (Jul 17, 2011)

I find that pH doesn't matter as much, so long as the KH and GH are low; I keep the KH in my tank at 1-2, and GH 4-5; I have crazy soft water, so I use a bit of seachem's alkaline and acid buffers to get pH to ~6, yet stil maintain some KH. For you, I'd suggest doing a bucket test on your RO water, and see where it's at after 24-48 hours first. Since you said it's unstable, I'd figure out where it stabilizes at before trying to change it, if it needs to be changed at all.


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## aquariam (Feb 11, 2010)

The kH under 2 wont hold anything. Just nitrification from a light fish load will eat that up in 3 days and drop your pH to 7 or slightly acidic. You do need to buffer R/O water. You want to use (X) buffer, if you're lazy and like premix like me, to get where you're going. It'll take your pH to (X) and lock it by raising kH, ie, alkaline buffer, malawi buffer, acid buffer, discus buffer (seachem)


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## Number6 (Mar 13, 2003)

xWingman48 said:


> Out of the RO unit, I have a pH of ~8 (not very stable), GH and KH under 2.


 your R/O system may be malfunctioning. The membrane should not be letting anything through. When you say under two, you think its near zero? Or above 1?


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## xWingman48 (Apr 8, 2008)

Number6 said:


> your R/O system may be malfunctioning. The membrane should not be letting anything through. When you say under two, you think its near zero? Or above 1?


It's near zero. When I last checked it, both the KH and the GH tests changed colors by the second drop.

Should I be worried about using phosphate buffers like discus buffer or neutral regulator? I've heard that phosphate buffers can bring about an outbreak of bad algae. I do have some live plants int the tank, and I plan on adding CO2 at some point.

The CO2 should help me keep the pH down, but I need something to get my KH and GH up slightly to prevent tank crashes right? What do you all start with?


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## Number6 (Mar 13, 2003)

ignore pH, and doubly ignore it since you will be adding CO2 soon.

Set the KH of the tank to be appropriate for the species of apisto you want to keep. Cacatoides are white water, so prefer a little KH where as some of the black water species will like it where it is as it comes out of the R/O filter. If you do have to add a tiny bit of KH back in, the "waste" water from the R/O system is wonderful triple filtered tap water and shouldn't be "wasted" ever! It's fantastic for plants, Malawi or Tang cichlids, etc. Capture that and cut you R/O water with a tiny bit of the "waste" water until you get the KH you want.

Please don't go for any "buffers"... if I could get the money back from what I wasted on "buffers" over the years I'd be able to buy myself a real treat!!!


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## xWingman48 (Apr 8, 2008)

Number6 said:


> ignore pH, and doubly ignore it since you will be adding CO2 soon.


One of my concerns with ignoring it is that adding in tap water, even R/O waste, is going to have a pH of 8.5 or higher. If I set the KH and just use CO2 to bring the pH down, then my water changes are going to be done with water that has a wildly different pH. My reservoir is only 50 gallons, so I'll be doing roughly 40% water changes.

Should I be worried about causing pH swings there, or will there be enough carbonic acid in the main tank to minimize the swings?

Don't get me wrong, I LOVE the idea of not having to spend money on buffers. --especially if they cause more harm than good. I just want to make sure I'm not going to be shocking my fish with a pH swing once a week.

Thanks for the quick responses by the way.


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## Number6 (Mar 13, 2003)

*xWingman48*
Good point... Maybe the word "ignore" isnt the right word. The water for your water changes needs to be close to the same parameters as your tank to add the water quickly. Now if the new water doesnt need to be added quickly then you can always use a thin water line (like an old air tube) and let gravity slowly add the new water. If it needs to be added back quickly then your water prep station needs to help you out. Peat or peat pellets can be very handy!


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## xWingman48 (Apr 8, 2008)

Number6 said:


> Good point... Maybe the word "ignore" isnt the right word. The water for your water changes needs to be close to the same parameters as your tank to add the water quickly. Now if the new water doesnt need to be added quickly then you can always use a thin water line (like an old air tube) and let gravity slowly add the new water. If it needs to be added back quickly then your water prep station needs to help you out. Peat or peat pellets can be very handy!


My reservoir is actually in the basement under the tank, and I have a pump in there to push the water back up. I'll have to think about my water changes for a bit. I could refill in stages by pumping in 5 gallons, waiting, pumping, waiting, etc. I may also be able to T my CO2 line and pump CO2 into the reservoir as well. ...that would mean I need another diffuser, check valve, etc, but in the long run it could be cheaper than buffers would be. (...and less painful than a many stage refill process)

Do Peat and Peat Pellets discolor the water at all? If not, then those might be a decent alternative.

Thanks!


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## ramsay22 (Nov 29, 2011)

There is a good article on aquarium water chemistry that covers this issue on the website of American Aquarium Products. It's worth reading


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