Is RO water stripped of sufficient trace elements?

cartouche · 06/16/2006, 01:52 AM

My LFS warned me not to use 100% RO water for top ups and water changes saying that it strips the water of all vital trace elements, he suggested using 50% RO water & 50% tap water? I gave him a strange look!

I thought (correct me if i'm wrong) that the salt contained the trace elements, but thinking about this he may have a point to a degree so I would expect to add some sort of 'trace element' supplements?

I find it strange that after purchasing an expensive RO unit I can only use it for 50% of the water....

Can someone put my mind at rest as to the best sollution....

bertoni · 06/16/2006, 01:53 AM

First off, find another source of advice. The salt mix will contain all that's needed, and tapwater can be very nasty. I don't use it anymore.

cartouche · 06/16/2006, 02:16 AM

Thanks JB, thats exactly what I thought!

To be fair he was just a lad, but I'm thinking he must of got his info from someone! This 'is' my LFS cause there only half a mile away, there is also 3 stores that are a chain of shops within 25 miles, I find them to business orientated... everything is top price etc etc... I have found a store that's an independant one, although its 50 minutes away (40 miles) its well worth the effort, the stock is superb!

Since using RO water all the polyps & mushrooms have virtually doubled in size and look much healthier, I really don't want any tap water in there at all.

delor · 06/16/2006, 04:43 AM

Part of what he said is true. The RO/DI water is devoid of any trace elements. I usually add a little buffer to mine to help correct for pH differences before adding it to my tank and to add back some of the essential elements that don't harm the tank.

BTW, not all tap water is bad, it mainly depends on where you live. Here in the midwest, our tap water sucks, mostly due to farm fertilizer run-off. The phosphates in my tap water can grow hair algae almost fast enough to see it grow!!!

Amphiprion · 06/16/2006, 10:29 AM

Unless you dilute the tank rather well with it, the demineralized RO water will have no appreciable effect. When water evaporates, all the minerals remain in solution to an extent, and become more concentrated. You are merely restoring the concentration when you add the RO water. The minerals that you need are already in the tank (or in the salt when you change the water). Agreed, do seek better advice.

Jocko · 06/16/2006, 11:02 AM

I think he was just confused about freshwater vs. saltwater. What he said is true for FW essentially. You wouldn't go filling up a FW tank with RO/DI or distilled water because THAT would kill the fish due to no trace elements. I guess the young lad has much to learn.

bertoni · 06/16/2006, 02:37 PM

There's no need to correct for pH differences with RO-DI water. It lacks any sort of buffering, so the tank's pH won't be changes, as the tank has a lot of buffering.

06/16/2006, 01:52 AM	#1
cartouche Registered Member Join Date: Mar 2006 Location: camberley uk Posts: 209	Is RO water stripped of sufficient trace elements? My LFS warned me not to use 100% RO water for top ups and water changes saying that it strips the water of all vital trace elements, he suggested using 50% RO water & 50% tap water? I gave him a strange look! I thought (correct me if i'm wrong) that the salt contained the trace elements, but thinking about this he may have a point to a degree so I would expect to add some sort of 'trace element' supplements? I find it strange that after purchasing an expensive RO unit I can only use it for 50% of the water.... Can someone put my mind at rest as to the best sollution....

06/16/2006, 01:53 AM	#2
bertoni RC Mod Join Date: Mar 2002 Location: Mountain View, CA, USA Posts: 88,616	First off, find another source of advice. The salt mix will contain all that's needed, and tapwater can be very nasty. I don't use it anymore. __________________ Jonathan Bertoni

06/16/2006, 04:43 AM	#4
delor Registered Member Join Date: Jan 2005 Location: Evansville, IN Posts: 1,124	Part of what he said is true. The RO/DI water is devoid of any trace elements. I usually add a little buffer to mine to help correct for pH differences before adding it to my tank and to add back some of the essential elements that don't harm the tank. BTW, not all tap water is bad, it mainly depends on where you live. Here in the midwest, our tap water sucks, mostly due to farm fertilizer run-off. The phosphates in my tap water can grow hair algae almost fast enough to see it grow!!! __________________ Surviving is different than thriving! Current Tank Info: Current: 90 gal RR reef tank, LED. Old:55gal RR, 440W VHO, 80# LR, LS, 20gal sump, SCWD. 5 gallon nano, 75 gal FOWLR

06/16/2006, 10:29 AM	#5
Amphiprion Premium Member Join Date: Jul 2005 Location: Mobile, AL Posts: 6,611	Unless you dilute the tank rather well with it, the demineralized RO water will have no appreciable effect. When water evaporates, all the minerals remain in solution to an extent, and become more concentrated. You are merely restoring the concentration when you add the RO water. The minerals that you need are already in the tank (or in the salt when you change the water). Agreed, do seek better advice. __________________ You've done it now, haven't you? Current Tank Info: 40g breeder patch reef w/ seagrass; 2-250w XM 10K; Vortech MP40wES & MP10wES; BM Curve 7 skimmer; carbon & occasional GFO

06/16/2006, 02:37 PM	#7
bertoni RC Mod Join Date: Mar 2002 Location: Mountain View, CA, USA Posts: 88,616	There's no need to correct for pH differences with RO-DI water. It lacks any sort of buffering, so the tank's pH won't be changes, as the tank has a lot of buffering. __________________ Jonathan Bertoni

06/16/2006, 02:16 AM	#3
cartouche Registered Member Join Date: Mar 2006 Location: camberley uk Posts: 209	Thanks JB, thats exactly what I thought! To be fair he was just a lad, but I'm thinking he must of got his info from someone! This 'is' my LFS cause there only half a mile away, there is also 3 stores that are a chain of shops within 25 miles, I find them to business orientated... everything is top price etc etc... I have found a store that's an independant one, although its 50 minutes away (40 miles) its well worth the effort, the stock is superb! Since using RO water all the polyps & mushrooms have virtually doubled in size and look much healthier, I really don't want any tap water in there at all.

06/16/2006, 11:02 AM	#6
Jocko Registered Member Join Date: Jun 2005 Location: Boston Posts: 595	I think he was just confused about freshwater vs. saltwater. What he said is true for FW essentially. You wouldn't go filling up a FW tank with RO/DI or distilled water because THAT would kill the fish due to no trace elements. I guess the young lad has much to learn.