RO water and buffering

[pnyklr3]

First let me start with this question: Buffering is the ability of the water to maintain a constant pH, instead of swinging, right?

If that is the case, what amount of buffering does RO water have? I am switching my tank to RO water (it's a long process so that I don't stress out the fish), and I was wondering if I need to worry about the buffering. I have noticed that when I test my water, the total alkalinty/buffering capacity has dropped.

My tap water has a pH of close to 9, is very hard (425 ppm), and the buffering capactiy is very high as well (300 ppm; test strips say to add pH minus, and I will not!).

My tank water now has a pH of around 7.8, hardness is 120 ppm, and buffering is 120 ppm. Is the drop in my water parameters going to stay steady with the RO water, or do I risk them becoming unstable? Might sound silly. but the holidays have fried my brain this weekend!

 

[CFC]

R/O water needs to be re-buffered and re-mineralised before it can be used, neat R/O can cause serious pH swings and lacks essential minerals that fish and plants need to grow properly. When using R/O water i use KENT R/O right and KENT pH stable to make the water suitable for my fish, you add the ammount of each powder back to match the conditions you require.

 

[blue_ram]

What CFC said, except I would go cheap, and use 50/50 mix of RO/ tap.

You could also go with African cichilids or live bearers instead. They prefer hard, alkaline water. Most barbs do well in hard/alkaline water. Also, see if your LFS keeps their fish in same water parameter as yours. If so, the fish have already been acclimated, and you can use your tap water. That way, I wouldn't have to mess with RO water and expensive membrane replacement cost. Constantly messing with water (like RO) tires you out. Eventually, you get tired of fishkeeping due to all that extra work. The trick to happy fishkeeping (at least for me), is to keep it simple and managable.

Look at the bright side. With water that hard, you might even get protein skimmer to work!

 

[pnyklr3]

Will a 50/50 mix have enough buffering to stop pH swings? Also, my lfs showed me a "pyramind" that had vitamins and minerals; is this different from what I need? I have also seen a powder at another store (don't go there as often because they are near a mall, and more expensive for the same things!) but I wasn't exactly sure of how to use it because there were so many options on the back.

Just my luck, I fell in love with Cockatoo Dwarf Cichlids! Although they can live just fine in my tap water, they prefer softer water with a much lower pH than what I have. To top this off, I drove just over an hour away to get them from a private breeder. I have learned from her mistakes: Out of 134 fry, only 1 was male. I am assuming that this is due to her using tap water with a high pH (very close to my tap water). Apisto sex is determined in the first 3 weeks, so I'm hoping that a high twmp and low pH in my growout tank will offer a more balanced fry ratio. Hence my fiddling with RO water!

Geez, when I get an idea into my head....

Thanks for the help so far. CFC, is Kent RO right and pH stable easy to find? I am torn between going the 50/50 route and all RO. Aren't there a lot of "yuckies" in typical tap water? I also don't have my own RO filter. I buy it @ 40 cents a gallon. It's actually cheaper than bottled water at the grocery store! Make my water changes at only $4 a pop.

 

[maestro]

Dont use all RO, Ro water had virtually no duffering capacity as all minerals have been taken out, the noramal acids pruduced through wastes etc will cause serious ph swings

Id use ro water and tap doesnt have to be 50/50, id but ro and premix it with tap, age it for a few days with a air pump to drice of chlorine and co2 (theres lots of co2 in tapwater and when you add it to the tank it escapess and in some cases the ph shoots up) and then add it to your tank

 

[pnyklr3]

Hmm, this reminds me of a post I had read about a "formula" for figuring the RO/Tap water ratio. Does anybody remember seeing this, or know what the formula is? It had something to do with drawing a square, and writing down your current pH and desired pH.

I was planning on going all RO, but after I saw my current parameters, I was concerned about going too far. I have only done 2 water changes @ 8 gallons each, so I am estimating that there is really only about 10-13 gallons in there right now. My pH isn't where I want it, but I don't want to risk the buffering dropping too far. Does anyone know of at what percent the buffering is lost? Like I said before, my tap waters readings (pH, Buffering, and hardness) are all through the roof.

Edit: After a search through the many pages of this forum, I found it!

Link

 

[pnyklr3]

Weird. I just tested some tap water that I had sitting out for about 5 hours. It still says that my pH is over 8.4, but the total hardness is about 25 ppm, and the buffering is still on the high side. The weird thing is, the hardness and buffering are lower that what my tank water was before adding in any RO water. What gives? This water was going to help me start some bacteria for my 10 gallon grow-out tank. It had been treated with stress-zyme and a declorinator.

 

[Bignose]

You can calculate the hardness of your water just by the proportions of RO to tap water. pH is also a concentration -- pH stands for the negative of the base 10 logarithm of the concentration of H+ ions.

However, the concentration of ions is very complicated when you are talking about tap water since there are so many different ions. It is not hard when you start with pure (distilled or RO) water and add one or two chemicals (see your favorite chemistry book) but when dealing with all the chemical species it usually doesnt come out very simply. Not only that, but you need some fairly expensive equipment to identify each chemical and their concentration. Actually, this is good since this is why our tap water has a buffering capability in the first place -- the complex of ions keeps the pH buffered.

Just about the only way to figure out the ratios for what you want would be to experiment. Just keep trying different amounts til you find what you want.