Automated water change system
I resisted use of any automated system due to having mostly small tanks which I liked to be able to easily move to the laundry tubs for occasional thorough cleaning. Solid plumbing of these with drilling and bulkheads would make this very difficult. Additionally the glass in a 5.5 gallon tank is not conducive to drilling. Since I was time limited to water changes every other week and wanted to do more frequent changes, I finally gave in.
Brian Shrimpton from
I made a couple of fixtures and they required
about 3 inches of tank space between two adjacent tanks. Not too bad.
My best estimate of CPVC cost is under $2 for each tank on the system.
A good estimate would be another $1 per tank for drip emitters, mainline tubing
and valves. This does not include cost of a pump or the ½ inch standard PVC
piping for carrying water to a main drain. If you use RO water in a reservoir
rather than city water a pump capable of enough pressure will be needed. It can cost upwards of $100. I would not recommend a model under 1200 gph
or capable of less than a 20 foot water height or pressure may be too low
for using emitters. Drain line using 1 inch PVC is another cost item. You will need one T in the main line for each
pair of tanks and enough elbows and pipe to suit your system arrangement.
My water change system had been to simply siphon from each tank into a 5 gallon bucket. The bucket contained a MAG pump to pump the water from the bucket to a drain. I have three, 32 gallon Rubbermaid garbage cans connected by bulkheads which collect my RO water in one fishroom. In one container in each array there is a MAG 1800 pump attached to a hose for filling tanks in that room. It is also connected to ½ inch PVC pipes running to the other 2 rooms to transfer RO water to those rooms. In the cold fishroom I have two more 32 gallon containers to allow water to adjust to the temperature of tank water in that cold room. (This may no longer be necessary with the slow flow of the drip emitters, but I need the extra capacity and have no extra space in my RO room). In one of those containers there is another MAG drive pond pump attached to a hose for filling tanks. That meant if the MAG 1800s would provide enough pressure, I could try the drip emitters using the existing pumps.
I bought some 4 gph emitters from http://dripworks.com and tried one emitter in
a hose from the MAG pump to see if the pressure was enough to feed water from
the emitter. The technical personnel
at Dripworks were a great help in selecting components and tools. My best guess was that the MAG 1800 pump would
put out about 7- 8 psi in the line based on its height spec of 20 foot. This
would mean that I should see about half the published flow rate of the emitter.
With the single 4 gph emitter in a fully open
flowing hose (to simulate other emitters dropping the main line pressure)
I achieved a slow but steady drip, almost a broken
stream of flow of about 1 ½ to 2 gallon per hour from a 4 gph emitter. That was consistent with my pressure estimate.
To use these emitters seemed feasible so I ordered
enough emitters, ½ inch mainline tubing, quarter inch vinyl tubing, Greenback
valves, elbows, emitter hole punch, some “Two Way Goofplugs” (60 cents for
10) and hose end connectors (to close the ends of each section of mainline
½ inch tubing) from Dripworks to do all three fish rooms. 
Based on advice from their technical department
I selected “Take Apart Emitters” since they worked well with low pressure
gravity systems. Stated flow was rated
4, 2, and 1 gph at 15 to 20 psi and I got about half that flow rate as anticipated.
Cost was under 25 cents each. Mainline
½ inch tubing was $12 per 100 ft roll. Quarter inch vinyl tubing (supposedly
more flexible but still a bit stiff) to connect each emitter with its corresponding
tank was $6 per hundred feet. These
prices were as of November, 2007. Aquarium
silicon tubing could be used to go to each tank from each emitter but the
black tubing should prevent any algae buildup in the system.
To punch holes in the mainline for the emitters I bought a “Miracle Punch”
from Dripworks for $15. It works well but caution must be used not to
punch the hose where the hose has been previously kinked or you can get a
leaky hole surrounding that emitter. The hose has some memory at such a location
and will give under pressure from the punch, not yielding a clean hole to
accept the emitter. There are “goof plugs” that can be used to seal any bad
holes. Use the double ended units since
these are large diameter and can seal a ragged hole very well. The drip emitters in my setup add about an inch
of water to each tank in an hour.
A Melnor Mechanical Aqua Timer ($15 at Home Depot)
in the main line tubing works well to allow unattended fill. There are electrical timers but this works fine
for me. It allows a time setting of
up to 120 minutes. This for me would
empty my reservoir and do a 15 to 20% water change. I added a second timer for water transfer to
my cold room since I am tired of forgetting and finding about 60 gallon of
RO water on my floor.
I put a “Green Back” valve 
($1.90 each from http://dripworks.com) for each row of tanks so
I could feed different harnesses of water to independent rows set up for different
species of fish that liked either very soft or moderately soft water. I simply turn on only the row that likes the
water currently in the Rubbermaid array. I
found these valves to be easy to turn, small and very nice overall versus
the large ½ inch PVC valves.
The pump seems happy to supply about 60 to 70 drip emitters simultaneously with no real impact on flow rate from the emitters. It may be good for even more emitters but I have not tried more since my largest reservoir only holds 90 gallons of water, enough for 60 tanks maximum. Emitters are sized for the tanks they feed. I use a 4 gph emitter for a 10 gal tank, a 2 gph emitter for a 5.5 and two 4 gph emitters for each 20 gallon tank. Each supplies about half the rated flow using the MAG pump.
Since I will not be moving 20 gallon tanks to the laundry tub for cleaning
I am drilling them to accept overflow bulkheads, but all smaller tanks are
fitted with overflow fixtures Components for a single fixture include 7 elbows,
one street elbow, one T and 5 short pieces of ½ inch CPVC for a total length
of about 24 inches. Cost of these components is under $2 per fixture.
Two fixtures are fitted between each pair of tanks. 
Fixtures, approximately 5 inches tall, hung on the end
of adjacent 5.5 gallon tanks feeding a 1 inch PVC drain
Flow is not sufficient to remove anything from the water surface. All joints are glued except the one connecting the elbow of the T to the upright from the tank. This allows easier prime of the fixture and swivel of the T section to mate with the drain line. The two elbows which support the fixture on the tank rim include one street elbow to allow a short span to fit over the tank wall. Street elbows are a few pennies more than normal elbows but do save some space and do not require a short section of pipe as is needed for connecting two standard elbows. They can be used for all angle fittings (one per connection though) but the added cost if you are making hundreds of fixtures can mount up a little. They cost maybe 5 cents each more than standard elbows.
Cutting PVC or CPVC pipe makes it well worth the investment to buy a cutter.
These are about $15 and save a ton of work over using a saw. Small cutters will handle up to 1 inch PVC pipe
(with considerable squeezing effort) but cut through ½ inch CPVC or PVC like
butter. Cutters and CPVC components
were purchased locally at a Home Depot.
I will still need to occasionally siphon the bottom of each tank but not long enough to make room for a full water change of 15%, just enough to remove bottom crud. Now I will be able to do more frequent water changes and not dump a ton of RO water onto the floor when adding to one tank while siphoning another. I believe that more frequent water changes will really improve egg production and fish overall health.
I also bought some tiny drip emitters I may install in egg boxes as soon as I can decide on an overflow system. Possibly trays allowing simple water evaporation will work. Another project after I complete the current one.
A Big Thank You goes out to Brian Shrimpton for fixture design and especially to Eric Bodrock for doing all the drain plumbing and drilling of the large tanks.
Bill Shenefelt