A Community and Forum For Aquaponic Gardeners

Tap or RO water

Which is better for my fish? Thanks

Replies to This Discussion

Permalink Reply by Jonathan Kadish NYC AA Chair on January 17, 2013 at 11:09am

Your fish will do fine in either, it is your plants that might need water treatment. It would depend on your tap's PH. If your tap has a PH in the 7-8 range it should be fine to use. Above 8 and you might consider RO or rain water.

An Aquaponic system is best kept at a neutral PH of 7 and will naturally tend to go from a high PH to a lower PH. So if you start at a PH of say 7.8, the natural acidification that occurs as a result from the bacteria will eventually have the PH drop closer to something like 7.

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Permalink Reply by Adam Vicknair on January 17, 2013 at 12:21pm

My system has a Ph of around 8 right now, due to my local tap water being highly alkaline. I used tap water but I bought a chlorine/chloramine filter for my hose so I didn't have to aerate out the chlorine before use. Before cycling the water was around 8.4. The change takes place really slowly, but from what I hear, the Ph will eventually end up dropping below the ideal range and you will need to buffer it up.

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Permalink Reply by Elan yadan on January 17, 2013 at 3:22pm

Thanks for the response. So for now I'm using tap water to change out their water. It used to be every three weeks now it's become a weekly chore.

When i get started I'll be looking to start w RO water so the last water change will have to be planned out w RO water ready to go right temperature and all.

Should I add Ca/Mg as it is removed thru the RO filtration process.

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Permalink Reply by Jacob on January 17, 2013 at 11:34pm

RO is better IMO. Nothing "extra" for you to worry about.

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Permalink Reply by Elan yadan on January 19, 2013 at 9:29am

Jacob, RO water is filtered out of Ca/Mg and needs to be supplemented back in for proper plant growth. That's why I was wondering if it would be ok to use by itself in an AP system or if using just plain RO water without added Ca/Mg would hurt the plants..

I learned the hard way what happens when not enough Ca/Mg is added back in. The plants show decencies very quickly and were not resistant at all to powdery mildew and I had a bad outbreak. Now I use double the recommended dose of Ca/Mg just to be on the safe side. Would hate to set my plants up for failure by using RO water and not adding some in if that's the case in AP as well.