How many gallons for automatic water changes?

[Gomer]

I currently use the LM3 auto-water changing setup on my tank. (Check my tank thread for some photos and a diagram)

Head pressure definitely affects the peristaltic pumps. When I used the pumps on my tank in the kitchen, I was pulling water from 70 feet away through 1/4" tubing and the rate was something like 1/5th of the flow rate with the container and tank in the same room.

if a peristaltic pump is truely sealed (ie, no back siphoning), this indicates that the motor is a bit weak and cant handle load well. The only way for headheight to effect flow is if it isn't sealed or if the motor rotation rate slows down.

 

[iani]

Tony, my cole palmer is affected by head pressure. It seems to be affected more when I have it going slowly.

 

[Gomer]

Hey Tony, could you do some of that fancy math for me?

Assuming the pumps I have will do at a maximum 5.6ml an hour; I would run the pumps 3 hours a day which would change about 1008ml. 1008ml x 7056ml. 1.86 gallons in a tank with about 25 gallons of water in it. That's only like 7.5% water change every week without the dilution factored in right?

While this is probably clear in your head, it isn't clear to me lol
This only remotely makes sense if you ment 5.6mL a minute.

5.6mL/minute * 60minutes/hr * (3hr/day)=1008mL/day
1008mL/day * 1week/7days = 7056 mL/week

If you sequentially removed 1008mL 7 times in a 25gallon tank,

1-(1-%change)^# of changes

1008mL * gal/3785mL =0.266gallons

1-(1-.266/25)^7 =0.072 or 7.2% change.

 

[kinetic]

thank you! time to drop some money =(