I've been doing some number crunching and came to some interesting conclusions that I thought could benefit some people who are getting into the hobby, like myself.
I've been reading and reading about how to setup my 65G tank and one thing that seemed to be general knowledge is that RO
water is better to use than treated tap water. Will treated tap water work? For the most part. Will RO
work? For sure. This of course requires either buying it from someone who makes it or buying an RO
setup. Option 2 seemed pricey to me so I found a LFS
selling it. To my surprise they wanted .50 cents a gallon. To get my 65G going with sump water included would have been around $37.50 plus gas getting there and back. That's not even thinking about water changes that will be needed.
Next option was purchasing a RO
unit. I lucked out and found someone selling this SpectraPure unit on craigslist used for $50. I wanted something quick and they said filters were just changed a few months ago. I had a TDS
test done on it to prove it was putting out 0ppm which it did. Anyways, on to the good stuff.
I checked my utilities bill to see what I'm paying for water. I'm paying $2.34 per 100cf for water and paying $3.80 per 100cf for sewage. Sewage is based off our water use. So I'm basically paying $6.14 per 100cf of water used. 100cf of water equals 748 gallons to put things in an easier measurement.
My water pressure at the RO
unit is 76psi which helps a lot with efficiency. Water is cold this time of year so that doesn't help. After a few tests I figured that for every 1 gallon of good RO
water I get I'm "wasting" 2.5 gallons. So basically it takes 3.5 gallons of water to make 1 good gallon.
748 / 3.5 = 213.714 gallons
213.714 gallons of good RO
water costs me $6.14
$6.14 / 213.714 = 0.029 cents per gallon
So as you can see the per gallon cost is very minimal even including the "wasted" water. At this rate it will cost me $2.18 to initially fill my tank. To do a 10g water change will cost 0.29 cents. Doing that once a week for a year will cost $15.08. Even with the cost of replacing filters and membranes annual costs shouldn't be much over $50.
If I were to purchase RO
from the LFS
I'd be at around $260 doing 10g changes weekly for the year.
: Even if you had to spend $200 on a new RO
unit it should pay for itself within the first year!