RO water question - Tropical Fish Keeping - Aquarium fish care and resources
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post #1 of 9 Old 03-02-2009, 01:41 PM Thread Starter
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RO water question

Hi, I've recently found out that the pet store in my neighborhood will give me as much free RO water as I can carry out. That being the case, I will, in the near future, be switching my tank over to RO water. However, I had a question that was not answered by the pet store employee. I have heard of different ways to use RO water, and I'm not sure what will work best. I was told by one person that they use strait RO water in their tanks; no additives or mixing with tap water at all. I have also heard that some people either mix their RO water with tap water to get some minerals back in, or they use a pour in additive (not sure what this is called, or who it is made by). Can anyone clear up this mystery for me? For some background information, the tank I will be switching to RO is a 55 gallon planted tank with 5 discus, 2 rams, and several cardinal and serpae tetra, pleco, and clown loaches.
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post #2 of 9 Old 03-02-2009, 02:32 PM
Are you sure ro water ph ;being a straight 7, is right for your discus ? Usually one might use ro to simplify ph problems.Whatever your purpose, i switched to ro slowly thru normal water changes. To supplement ro water you add ro right at 1ml per gallon, if your replacing evaporated water you need not supplement because water evaporates not min's however use common sense after so much of this you'll have to supplement. If you take out 5 gal's and add 5 gal's of ro use 5ml of ro right by kent.Your tanks stock sounds nice. Most people can't keep discus well muchless with other fish, good job. Think this change thru first.
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post #3 of 9 Old 03-03-2009, 08:32 AM
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keep in mind RO water is void of any essential nutrients. you will probably need an additive to make up for it. I use a ratio of about 50/50 (RO/tap) for my current tank
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post #4 of 9 Old 03-03-2009, 11:52 AM Thread Starter
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I'm pretty confident that a ph of 7 will be fine for the discus. I have not had them for too long, and they seem fine in my tap water, which is a ph of 7.1 or so, a gh of 150 ppm and kh of 80. The fish store that I bought them from uses unconditioned ro water for their tanks, and they seem to be successful, but I was told that my other fish might require some mineral content in the water, which is where my confusion arose. I think I will stay away from using strait up ro water, but now I have to figure out if I want to mix it with tap or a conditioner of some sort. Also, when I do get a supply of RO water, im guessing it will be a lot cooler than the 84 degrees my tank is set at. Should I stick a small heater in the bucket of RO to warm it up before hand? I know the discus are very finicky about temp changes, I usually try to match the temp of the tap water I use to the temp of the tank, with success so far.
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post #5 of 9 Old 03-03-2009, 12:43 PM
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RO is fine, probably better for Discus depending on your tap water. you will want to supplement your RO water with a powder mix or with tap water. the reason being RO water has 0 alkalinity, so the slightest alteration in water quality could cause significant pH swings. Find the Kh and Gh of your tap water and supplement the RO water so Gh and Kh are about 3. Also in my experience RO water tends to have a pH of 6.5-7.0. a powdered mix or tap water containing minerals should buffer this to 7.0 then our may use a peate sack to acidify the water if you want to.
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post #6 of 9 Old 03-03-2009, 02:18 PM Thread Starter
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Thanks for the input guys, I think I'm going to gradually start working RO water into my tank through water changes. I think I'll try using 1/2 RO and 1/2 tap, as I try to stay away from using any kind of chemicals in the tank unless it's absolutely necessary.

BTW- that's very good advice about putting in strait RO water to top off the tank, what with the minerals not evaporating. It makes perfect sense, but I don't think I would have thought of that one.

If anyone has any other advice or information on RO water, please keep it coming, I'm learning a lot.
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post #7 of 9 Old 03-03-2009, 08:39 PM
Hi,well thats how i did it and it couldn't have worked out better. I now wonder how i did it in the past. Youi'll have to use ro right eventually, true your ph may end up in the low 6's or worse like even 5's if you don't. I heat my water and add my ro/r, black water extract and air right in the water jug. A good trick is to microwave like a large cup of water to boiling and add it to your water just to speed things up.Well by now and good luck.
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post #8 of 9 Old 03-04-2009, 07:26 AM
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Personally, If my Discus were thriving in tapwater with only conditioner to remove or detoxify ammonia, chlorine, and chloramines then I would be pleased. I keep five Discus in moderately hard water with Ph of 7.4 with three weekly water changes of 25 to 40 percent .They have been doing well(knocks on wood) for nearly two years. They were tank bred specimens as opposed to wild caught and adapted well to water straight from my tap. If I were to attempt to breed the discus ,then I might consider the use of RO water to help soften the water. If I were to do this ,I would do as many others and get a 35 or 40 gal rubbermaid tub (wheels optional) and mix the water for water changes in the tub and place a submersible heater in the tub along with aeration. In this way I could expieriment with the mixture and once it was what I desired,, I would use this storage water for water changes. I would probably start with 50/50 mix of RO and tapwater. Hope some of this helps.

The most important medication in your fish medicine cabinet is.. Clean water.

Last edited by 1077; 03-04-2009 at 07:29 AM.
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post #9 of 9 Old 03-19-2009, 11:50 AM
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RO water as far as I am concerned SHOULD NEVER be used straight. Most RO systems have a conductivity output of >10, normal tap water will be around 500(this meaning, if you drop your toaster in RO water and then put your hand in you will not get a shock). Pure water will not conduct electricity. Not knowing the condition the RO system that you are getting your water from DO NOT TRY THIS. Without adding any conditioners you are in danger of leaching your plants and fish. There are chemicals that are in RO systems that if the system is not being kept right can be dangerous to not only your fish but you. As far as measuring its PH, it takes a meter that costs upward of $1000 and must have daily maintenance in a well equipped lab to get a good PH read on RO water. PH is a read by measuring free ions. Being RO has little to none a store bought test kit or strip kit will give you a reading you should only be afraid of. That said the PH of RO water will swing very easily. Any PH adjust that you add will have a HUGE affect on the ph of your tank because you are adding active ions to an environment that has none. There are a lot if filtering methods out there for tap water. The fad as of late seems to be to use RO. As a chemist dealing with RO systems for the last ten years this is not one I would recommend to the fish loving community. The spring water systems are a much better fit.

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