Help me design an automatic water change system for my 125G tank

[Greg5OH]

Few prefaces.

-Im on a well and septic. I change water every 2-3 days manually with a hose, 40%, Straight from my tap, just set the tap valves to reach 84F outlet temp. Discus have been spawning so they seem to like things in the tank. So no holding or aging barrels.

-The tank is not drilled and does not have a sump, im not opposed to either if it makes things easier

-I do not want continuous water changes. Bad for a septic to constantly have liquid going into it

-The tank shares a wall with my bathroom. The 4" sewer clenaout plug is to the left of the tank, and the hot and cold pipes are to the right. Just need to sweat some T fittings on. Very easy access to both.


I was thinking of using an apex by neptune systems-popular in the reef world. Its just quiet expensive. I dont have the time to teach myself how to do the reefpi thing. Id rather spend the money on a good product if it works the way i want it to work

Since there is no holding tank, no sump and its not drilled, for draining Im thinking of just having a pump in the tank somewhere,
and grey sched 80 piping running to a Y fitting (so i can still have a cleanout there), which branches off to first a P trap, then a solenoid valve.

OR-do i just drill the top of the tank and plumb it to the drain, but still have a solenoid valve that opens to allow it to drain, and just have the freshwater run for X time to do a "fixed time continuous change"?

My logic for the changes is as follows, keeping in mind redundant safety systems.:

I assume I can set up some safeties in it,
for example:
Drain sequence:
See that water is "full"
open drain valve,
start drain pump (located in the tank)
turn off drain pump when low level sensor tripped
close drain solenoid valve

Fill tank:
see that full sensor shows level low
see the drain solenoid is closed
open fill solenoid valve (water temp preset at the outlet)
turn off fill solenoid when full sensor shows full.

I would have a manual ball valve on the fills just in case the solenoids fail, I can shut the water flow off in an emergency.

I would also like to run a redunant safety sensor on the fill.

[alron2]

Greg you are not the first to ask this question. Use the search feature at the top of the page and start reading~. Lots of information on this subject. Most people are unable to achieve success with auto watering systems and give up. Lots of money, not as good at removing all the waste as manual operation, but research it and see what you come up with. I was one of the ones that gave up.
Ron

[Greg5OH]

Ah that is true about the waste on the bottom. I have gone BB so it is alot easier, most of it collects in this one area...perhaps I can hook up a pwoer head that would blow across the bottom durign the drain cycle to put the waste up and have it flow out the drain...
Or at least reduce my hose work from every 2 days to 1x a week?

[Greg5OH]

At the end of the day, the thing I dread the most is filling the tank. As I constantly have to either sit around and watch it, or gauge how long I have left till Im full, go upstairs, then run downstairs every few minutes to monitor. Too many times I have come milimeters from spilling over.

THe draining manually and vacuuming the bottom is not bad, Vacuum for 5-8 minutes, then the rest just let it drain..but filling I would love to have it semi automated.
Push a button, thermostatic 3 way valve will regulate to teh temp I want, solenoid opens water flow, then float/optical some kind of sensor will shut off water fill when done.

[Cove Beach]

I have a cheap semi solution for your fill problem. First you will have to time your fill from a specific point. Once you get a good number, you can go to HD or Lowe’s in the lawn and garden and pick up a sprinkler timer. Hook it up inline with your fill hose and set it for short of your fill time. It won’t eliminate all your trips but if done right it should keep water off the floor. I used this method for several years to control my r o water drum.

[alron2]

I would modify Mark’s plan and purchase a sprinkler system timer instead of a single sprinkler timer and use it to also control a drain value making it even more what Gred asked for. For safety consider the following two options (1) drain the tank from the top third of the tank in case the drain value fails to close so you will not completely drain the aquarium; (2) install a float value on the end of the input line so if the incoming value fails to close you will not flood your house.