Adding RO water directly at 50% water changes

[tam]

You can get square ones too, depending how much you want to hold: Water Butts - Water Butt - Slimline Water Butts - Wall Mounted Water Butt

 

[MichaelJ]

One thing you should/must do with RO water BEFORE using is test it. This is why storing RO water before use is such a good idea. Many people have suffered "fish issues" where they thought they had 100% RO water when in fact they hadn't due to failed RO unit.

I went to an "open day" in local fish shop where they showed & explained all their backroom equipment. They had a large pumped RO unit providing RO water that stored RO water in large 100l water butts. Before release to customers it was tested for chlorine and ammonia and TDS levels. The reason for this is if the De-chlor pre-filter wears out or RO membrane wears out (or leaks which is more common) you get free chlorine and/or ammonia (ammonia from chloramine breakdown) in the RO water, which can be fatal to fish. There was a digital water gauge at input to RO system and each filter/RO membrane had the water gauge reading for when it was to be changed.

RO water that they were going to use internally in their tank systems was not tested, they just dosed with Prime to neutralise any chlorine or ammonia present. They just pumped 100l of RO and 100l or dechlorinated tap water into their system and any excess overflowed into the drain.

Very important points @ian_m. The carbon stage is what actually removes the chlorine. The higher the chlorine content the lower the lifespan of the carbon cartridge - the relationship is just about linear. With my small RO system, 0.5 ppm of chlorine in the water source makes the lifespan of the Carbon cartridge about 720 gallon, at 1 ppm its 360 gallon.... Our city water is ~0.25 ppm so that should theoretically be 1440 gallon give or take... When When the carbon cartridge fails and the chlorine starts to enter the membrane it will dramatically reduce the lifespan of the membrane. Yes, always monitor your RO water! A sudden or gradual spike in TDS/EC is a good indicator that things are going south and it's time for replacements, but you can't rely on TDS/EC alone with chlorine as the increase usually would be below 1 ppm (below the tolerance of the measurement) which can still be detrimental to livestock. At least towards the end of the lifespan of the cartridge, it's a good idea to add a bit of dechlorinator (such as Prime) to the RO water - keep in mind that it will raise the TDS a bit due to the Sodium sulfite or Sodium hydrosulfite which is used in dechlorination.

EDIT: Chloramine is a different beast. The Carbon filtration stage will usually not be efficient enough to remove Chloramine and an extra filter stage - using catalytic carbon as opposed to the less efficient activated carbon - in addition to (or instead of depending on your system) the regular Carbon stage will be needed. If there is a good chance your water is treated with Chloramine you most likely need that extra stage.

Cheers,
Michael

 

[MichaelJ]

I tend to refind my posts by using longer terms or by <"using analogies that aren't likely to be used by anybody else">. This doesn't help in finding other members posts, unless I can remember who the member was or some phrases that they used.

Well, you also seem to have the memory of an elephant.... thats helpful.

My brain is like Swiss cheese when it comes to remembering my posts around here.

Cheers,
Michael