> In discussion regarding 100% water changes in place of
using filtration...
Basically, what would it cost if you turned your tank into a
sink, and just left the tap dripping?
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Did the math for my 135G...
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Option 1 - 100% water change each day.
Capital Investment: $85 + ($100 ??)
Monthly consumables: $18.75
Maintenance hours: 0-2/month
Assuming, flat $30 per 10K gallons of water/sewage; $30 per
Matrix Carbon cartridge (20K gallons); and $10 for a 2 year
(reusable) 5 micron sediment filter.
Capital Investment includes ($25-Timer, $20x2 filter
housings, $15-fittings, drain tubes, tax, etc.)
?? - Depending on how fast you can flow the water change,
you may need to buy something like a Magnum 350 to clean
particulates that settle. You'd likely have to use it every
week, or two, so the consumables are negligible but the
capital investment is one my filtration based setup doesn't
need.
Consumables: Tap Water, Carbon and micron filter cartridges,
and electricity at $0.15 per kWh.
Variance factors.
1) Few pay a flat price per 10K gallons of water. It is
usually sold in "blocks", or any part used thereof, within
the billing period. Thus, if you are constantly over by 2K
gallons, and paying for 10K, you can dedicate 8K to this
without cost.
2) Is a 100% change per day excessive? I dunno. Cut the
cost in half if you can do 100% every 2 days. Or, in 4.
Easy enough to determine, get one of those Ammonia patches
and stick it on the glass. Adjust accordingly.
3) If you want water movement you'd have to add a power
head, and it's attendant power consumption. A 15-20W unit
should do a freshwater tank nicely, but it ups your monthly
consumables cost by $2.15.
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Option 2 - Pump and filters.
My tanks "cost".
Capital investment: $330
$95 Quiet One - 85W.
$60 20" "Big Blue" housing, particulates
$60 20" "Big Blue" housing, bio
$85 Automated water changes, 5GPD
$20 Pipes, fittings
$10 Craft felt bio-filter "cartridge"
Monthly Consumable: $11.37
$0.69 Tap water, 5GPD
$9.18 85W Pump, 24x7
$1.35 particulate cartridge, $32, 2 year cycle
$0.15 Diatom powder
Maintenance hours: 0.25/month (15 minutes).
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Conclusion:
Using a pump and filter system saves $7.38 per month in
consumables. That pays off the $245 higher capital
investment in about 30 months, at 5% interest. That vs. a
100% water change per day.
At a 50% change per day, payback is about 5 years. 25% per
day, just under 10. How low can you go? Goldfish in seem to
live in crampt bowls all across the world, rescued with a
water change every week, or so. A kid's goldfish bowl is a
remarkably high bio-load "tank".
Rather than face a 10 year ROI (at 25% water change per
day), it is better to go with the drippy sink model. Few
consumer grade filtration products live to the 10 year mark
without fail. My system is of industrial construct, so it
has a 50 year life expectancy. My freshwater tank just
passed it's 10 year birthday, maybe I should've celebrated
that a bit more.
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