R/O for freshwater

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smilla4

Aquarium Advice FINatic
Joined
Dec 6, 2003
Messages
640
Location
Seattle
I was wondering if anyone here uses RO water for freshwater tank? Do you use straight RO or mix it with tap water? What is your chemical/additive of choice?

Someone told me today he used novaqua, others have mentioned "ro right".
 
well i don't personally use it, but ive considered it so ive done quite a bit of reading. it is fine to use r/o for your freshwater tank, except you either MUST use an additive to put trace elements back in the water, or you must mix it with tap water.

you probably know that tho.

sorry, that's all the advice i can offer. :?

-brent
 
Unless your tap water is really bad, I wouldn't spend the $$ for a FW application. If you have very hard water, and are keeping discus for example, you could mix the RO with the tap to get the desired pH and hardness. If you're concerned that your tap water has contaminants in it that will affect the health of your fish, you'd need to use RO Right with the RO water to bring the mineral content up to where it needs to be. Straight RO water will be pH 7.0 and have no buffering capacity...pH will shift very quickly.
 
My tap water kills my fish; it's horrible. I use ro water that I buy from a machine at Walmart. According to the maintenence chart, the TDS reading is 6. I use it for my African Lake Malawi tank, so to condition the water I use 1 tsp. each of sea salt, epsom salt, Proper pH 8.2, and CichlidVital per 5 gallons of water. I have a ten gallon tank with a powerhead, heater, and air pump that I hook up; I let the water sit for a couple hours which dissolves the salt and raises the temp of the water.

It may be a bit much for just a freshie setup, but introducing new cichlids to the setup is a pita and I can never find ones large enough to replace the ones that died. Plus, at $9 a fish (or more for larger specimens), I really can't afford to not take good care of them.

I look at it as practice for my salt water tank I'm going to get someday :wink:
 
I haven't used it yet but I may be using it when I set up my African rivers community in September. The fish are all fairly used to a pH of 7.0 or lower according to my research, and there's a snowball's chance in hell that the pH of the tap in Maine is going to be that kind to me. ;)
 
I bought RO+DI to lower the hardness and ph of my tap water. I sort of use a 50/50. My RO system has a few different stages. I about 4 gallons through all the stages. This removes almost everything from the water. The other 4 gallons I put through only the 1st 3 stages. These are only carbon filters and should remove chlorine and other chemicals from the water (my water is also said to have lots of insecticides in it), and leave most of the minerals and electrolytes.

RO is kind of expensive and a lot of work. It's probably best to find fish that fit your tap water conditions. If you need RO then ebay the only way to go. I think $160 or $180 is the best I've seen outside of ebay. I got mine for about $100 (with shipping). I just barely bought my brother an identical one for only $60 (with shipping). When I saw the deal I couldn't pass it up. If you don't need it right away be patient and wait for the right price.
 
Straight RO water will be pH 7.0

loganj,

I'm no expert, but I believe your statement is incorrect. RO water without any additives is acid. I checked the water I purchased from my LFS and the pH is about 5.0. Adding R/O Right (or equivalent) allows the RO water pH to be adjusted as necessary for the particular needs of the aquirium.
 
I mix about 10 gallons of DI water in my 55 gal tank during water changes to lower the hardness for my angels. I can't think of what the name of the addicive is that I use, but you definitley need to put trace elements back in the water. Straight RO water only is a no-no though, I don't think your fish would last very long :roll: Check out the artivles page here on AA for a introduction and information on RO-DI water.

Also, I'm not sure about the ph thing, but I'm leaning more with loganj. The pH of water is in it's "neutral" form 7.0. Isn't that what RO is, just "pure" water. Makes sense to me, but I'm not sure. Hope this helps some!
 
I suppose it's possible that RO water could be acidic. RO/DI water should be neutral. Pure water should be devoid of both acids and bases. My water from the RO/DI unit tests neutral. RO/DI water will very quickly shift to an acidic pH with the addition of the smallest amount of acid because it has no buffering capacity at all. That is one big reason not to use it in your FW tank without an additive to give it some buffering capacity.
 
Please, I really don't wish to be arguementative. But loganj is right about RO water being 7.0 - or at least it is supposed to be. The RO water from my filter is 7.0. RO water has very little or no buffering capacity. This means that it takes a lot less to change the ph. My guess is that the water that you bought, pokrface, had a little of something in it and this threw off your reading.

edit: sorry I just repeated eveything you said loganj, you must have posted a split second sooner.
 
I have very hard tap water. The pH out of the tap is 8 or 8.2, and the general hardness (it's been awhile since I did hardness tests on straight tap water, so I can't quite remember) is about 13 dh.

I get RO water from a machine in my grocery store. I don't check its pH every time I get it, but recent readings have been 6.6. I have two 5.5 gallon tanks, so it's not a big hassle to get a gallon or two of RO water a week.

I mix half tap water and half RO water. I don't add any additives. I did buy one bottle of RO Right, but I took it back. It only added one dh to the water, and I figured I didn't need it since i mixed with tap water. The general hardness (of the mixed waters) is 5 dh and pH 7.2, and 6 dh and pH 7.4 (two tanks).

I have betta tanks, and it's been working out well for them. I did pH tests frequently when I first started doing this, and I don't get any pH swings. The bettas seem happy and healthy.
 
I also have horrible tap water. It kills babies and makes my adults (bettas) prone to illness (if i'am ever late on water changes). I'am trying to save up for an RO- there so expensive!! 8O
I was told to just mix it with tap water.

ashley
 
I have a mix of both RO and tap. I chose RO to lower the hardness of my water and it worked like a charm, however, I've read plenty of posts indicating you should always have some tap water as it does contain certain beneficial minerals that fish like as opposed to the Chlorine that everyoen fears.

I think I'm roughly at a 50/50 mix right now, but possibly a little more RO than tap from when I started. I noticed no behavioral differences with my fish, but my water hardness test sure noticed the change.
 
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