Re: [Killietalk] RO unit

["lee Van Hyfte" <littleleeper23 at hotmail_com>]

Hi Gerald,

If you are using well water you will need to avoid the CTA membranes.  The 
CTA membranes require chlorinated water to function.   The CTA's generally 
have lower rated outputs and cost more too.

Most membranes available are destroyed by chlorine and use carbon block 
prefilters.  As I recall they are called TFC membranes.

The water coming from a functioning water softener will extend the life of 
the membrane.  You will not want to reuse the waste water though.  It will 
essentially concentrate the salts.  NOTE: Maybe useful in brackish hard 
water species.

If using straight well water you can still get excellent life out of your 
membrane.  I had one on straight hard water that lasted 3 yrs.  Still 
producing 14 mS water.

A back flush kit is a must no matter what system you purchase or how you run 
it.  The unit should be back flushed at least monthly and frankly the more 
the merrier.  It just takes a few minutes.   The back flush greatly extends 
the life of the unit.

Pressure is an issue so check your total output pressure on your well pump.
The average membrane rated for 125gpd is assessed with water at 70F and 
70PSI.  as temps drop and pressure drops the total output and efficiency of 
the membrane greatly decreases.  My fathers unit is rated at 125gpd but at 
40psi and 55F it is only capable of 50gpd.  The total conductivity is a tiny 
bit higher but is still favorable at >20mS.

If you want to enhance efficiency a pressure pump can be purchased.  Less 
waste water to water output.  Pressure pumps are not cheap either.

I strongly suggest a float type valve on the output storage tank as this 
will prevent you from flooding your basement.   THEY WORK WELL!!!!

I also suggest you review the adds on EBAY as you can get really nice 125gpd 
units for about $100-$125 shipped.  Avoid the ones that have the 3gal. 
storage tanks as this only adds to the price and I am sure you intend to use 
more than 3 gpd.

I strongly suggest either a TDS or conductivity meter.  These should be able 
to be purchased for about $35 or so on ebay and usually from the same 
company you buy your membrane.  This not only gives you a good indicator of 
water output quality but also that of your tanks you intend to use R.O. on.

You want to avoid shifts of >10% down or >20% up.   Say you get a reading of 
100mS on a tank and you want to drop the conductivity to 50mS  it will take 
several small water changes to get there.  day #1 you drop the total 
conductivity to 90mS Day#2 you drop it to 81mS  you get the picture.  visa 
versa increasing day 1: 100 to 120 day 2: 120 to 144.   These 
recommendations are to reduce the likelihood of osmotic shock.

Because my water is sooo terrible I prefer to reconstitute my R.O. water 
rather than mixing tap back into it.  I use kent Marines R.O. right and kent 
marines discus essentials.  They add macro and micro nutrients back into the 
water.  The discus essentials will last greater than a year.  the R.O. right 
depends on what level you add into the R.O. Both are available from Fosters 
and smith at reasonable prices.

last notes DI filtration after the output will drop conductivity to about 
2-3mS. The DI unit if you opt to use one will need replaced at least every 6 
months or so.

meters read in TDS=PPM  and the conductivity meters read in mS or 
microsiemens.   Both the TDS and mS meter actually use the same technology.  
the TDS meters are a conversion of mS into a ppm reading.  By definition mS 
is always a more accurate depiction of the water's qualities.  However, TDS 
is more widely used.

let me know if you have further questions.

God Bless, Lee Van Hyfte <><

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