RO Water Use Procedures

[PaulineMi]

I tend to slowly mull things over before doing them.  Being in RO "mulling mode" now, I'm trying to find info on what using RO water entails.

There is a post on this forum stating it's best to mix RO water with aged tap water when needed as RO water doesn't store well.  Having read that it takes hours to collect RO water how do you do that? Is the unit run overnight for use the next day? And how does one get and keep the RO water to the required temperature? Is pre-planning and immediate follow through required?

In my mind it seems like a RO barrel is needed, the water is collected over a period of hours, the temp is brought up over an additional period of hours and then it is somehow mixed with aged tap water that's in another container. Of course the correct mix of RO to tap would have to be determined.

In other words, for example,  a 50/50 blend for 100 gallons of WC water would require a half filled 100+  container of tap water, a 50+ gallon container to collect RO water, then pumping the RO into the tap container then filling the tank that the fish are in. 

[PaulineMi]

Continued as my Kindle wouldn't let me edit

Would the water going through the RO unit be collected from the cold water faucet only? Heating that much cold water and the electric bill is a concern.

[Mugwump]

I just filled my tub half way with regular water, filtered through carbon/sediment filters, ..tossed in a heater, then added the R/O ...mine was 100gpd unit, but I could get about 7 gallons an hour out of it....when you had enough R/O to fill the tub...did the water changes...yada yada....I never reconstituted, or anything....IMHO, don't try to over think it....blend it and use, if you're a little off the 50/50...no big deal....the tds's will fall like rain....my R/O tds was under 10....take a cup of the blend and test to get the resulting tds of your water.....

[Frank The Plumber]

I used a float valve out of the RO unit into a container. You can get them at aquacave.com. When the tub is filled it will shut off the float valve, I had always monitored my actual TDS because I use Chicago tap which has a TDS level of around 220 to 250 and can bounce back fairly fast. If I used straight RO I rebuilt it. If you get the TDS down very low in water it will absorb vital minerals to seek balance. You can actually damage your fish by using straight RO and not reconstituting it. This is why they blend it, but the blend water being used is fairly soft too and doesn't bounce back too hard. If you set up a batch play around with it to see what you have from your source and what you are blending it into. A cheap TDS pen or meter will keep you out of trouble and a decent pH meter will help as well. You are starting to get a very nice collection of fish and not knowing the numbers when adjusting water parameters could hurt them. It's worth the money in your case to have these meters. If it does not bounce around too much the blending will work fine.

[BillT]

Hi Paiuline,

There are many ways to do this and many little tricks you choose to use or not use.

Mug mixes RO with his tap water to get his desire water conditions.
Another approach is to use the RO water as a "pure" source of water, keep it "pristine" by not using un-RO-ed water and reconstitute it with known chemicals. This can be more difficult but also reduces the source of certain kinds of problems (such as variability on the quality of the tap (or whatever source) water source. This can be more problematic for some situations than for others. Labs tend to use this approach just to remove a potential source of problems.

RO water can be stored in large containers that can be kept filled automatically.
Many RO machines will have a special valve that will allow them to kept plugged into pressure but not pressurizing the membranes when not in use. It is a plastic fitting with 4 tubes going into it.
This allows the output of the RO machine to be connected to a cheap float valve ($5-10) so that it will fill to the valves shutoff level and then turn off pressure to the membranes.

Your membranes are one of the major expenses of using an RO machine. You should check on their replacement costs. They have to be replaced periodically. The particular schedule for this varies greatly.
They can get "clogged" up resulting in reduced production.
Hard water will clog up membranes more quickly than soft water because there are more molecules in the water. If you use a water softener using the water from that would make your RO membranes last longer, but would probably require using a motorized RO machine.

Or they can deteriorate so that they pass the molecules they are supposed to block out and the RO water is not "pure".
Chlorine in water getting to your membranes will cause them to deteriorate. Charcoal filters are used to prevent this and are usually built into the machine. It is good to put additional filters up stream off the machine with test ports (valves) in between to test the output of each filter with a chlorine test. The first filter should go out first but the membranes will be protected by the secondary filter(s).

I live in an area with very soft tap water (~30 ?S) and have two charcoal filters in front of my RO machine and I have been using the same set of membranes for 5 or 6 years.

Would the water going through the RO unit be collected from the cold water faucet only? Heating that much cold water and the electric bill is a concern.

The proportion of water than will get rejected from be decreased if the temperature is increased, this will save on the cost of water, but require using your domestic hot water supply. If you are going to use the water immediately that heat will go to your fish, otherwise?

Digression:
An RO machine works by pushing water through a membrane with very small holes that will mostly only let the water molecules go through, keeping most salts and other impurities on the source (pressurized) side of the membrane. This requires energy because making the water molecules go from the source side of the membrane where their concentration is diluted by the presence of the salts and other retained molecules to the produce (low pressure) side of the membrane where the water molecules are more concentrated is going in opposition to the way osmosis works (a basic physical property of solutions). The pressure of the water line (usually around 60 psi I'm told) provides the force for this. Alternatively fancier RO machines will have pump to apply higher pressures to move more water faster.
End Digression:

[PaulineMi]

Thank you Jon, Frank and Bill for your explanations. Interesting information.

I am using well water with a TDS of around 350. Frank I have TDS, pH and conductivity pens and will be sure to use them to determine what proportions of well to RO should be used. Is there a redundancy in the pH and conductivity pens?

If I get an RO unit (birthday is soon) it would be set up after the water softener. Water coming in from the well goes through a carbon/sediment filter before going into the softener. The RO water would be reconstituted with the filtered well water like Jon does it.

Bill your digression was helpful.  I had seen pump options available and had wondered what they were all about. I'm looking at a portable unit that can be connected to the faucet as opposed to being plumbed in.  A pump can be added later if needed. Hopefully I can bypass that option.

From Liz and other discus people I've learned that fish can go from low pH to a higher pH safely. However for the opposite slow acclimation is required. I may start a new thread with some thoughts and ideas I have on that topic.   Jon....what was that about over thinking it. Lol.

[Mugwump]

T   Jon....what was that about over thinking it. Lol.

LOL...I know....

[BallAquatics]

It does take a bit of thought when first starting out, but once you get your mixes down, and a little experience, it just becomes second nature.  You might want to check around with some of the local companies as to what you can expect your cost per gallon to be to produce RO.  That's what has always kept me using rain instead of RO.

Dennis

[BillT]

Is there a redundancy in the pH and conductivity pens?

Only slightly:

The conductivity pens will probably detect most buffers and pH affecting ions as a contribution to the conductivity since charged molecules can transmit current through the water (conducting, therefore conductivity).

The pH pens will detect hydrogen ions (H⁺) and will ignore most other ions. Other ions may indirectly affect the detected pH by affecting the ionization of other molecules that can bind or release hydrogen ions. This is more of an ion to ion interaction rather than the meter detecting them directly.

[PaulineMi]

My mistake....I meant to ask if there was a redundancy in the TDS and conductivity pens.

[LizStreithorst]

Conductivity is a more accurate measurement.  TDS measures all dissolved solids.  Conductivity is a measurement of minerals that conduct electricity.  If you keep up good WC one measurement is as good as the other.  This is my opinion.  I could be wrong.  Other people know more than I do.

[PaulineMi]

From what I've read you are correct Liz.  I will just concentrate on the TDS part and all should be fine.

[Mugwump]

I just filled my tub half way with regular water, filtered through carbon/sediment filters, ..tossed in a heater, then added the R/O ...mine was 100gpd unit, but I could get about 7 gallons an hour out of it....when you had enough R/O to fill the tub...did the water changes...yada yada....I never reconstituted, or anything....IMHO, don't try to over think it....blend it and use, if you're a little off the 50/50...no big deal....the tds's will fall like rain....my R/O tds was under 10....take a cup of the blend and test to get the resulting tds of your water.....

From what I've read you are correct Liz.  I will just concentrate on the TDS part and all should be fine.

Moving right along......

[PaulineMi]

Lol.....it only took a dozen posts.   

[LizStreithorst]

You worry too much you silly goose.  Just do it.