Drip vs. Bucket for Water Change

[Alight]

Zero for NO3 might be a problem for your plants (great for the Discus, though). I know it would be for mine. Even though my Rotala likes low nitrates, when I change water too often, it gets unhappy, and grow more slowly.

[scans]

Plant growth is OK...not spectacular...but OK !

[standoyo]

drip system for planted tanks? wow... a first for me...please post a pix of your tank...

[scans]

I'll see what I can do this weekend...

[sleonard]

...you cannot assume that the instant the new water hits the tank it is 100% mixed with the tank water so that before the drip overflows its homogeneous with the rest of the tank. The amount of actual wasted new water will depend on the rate of drip AND the rate of mixing in the tank before the water overflows. I'm not sure you can mathematically calculate the questions raised here with 100% accuracy.

The mathematical model I offered gives an estimate of the amount of water changed with a drip.

The equation quoted earlier does give an approximate % change for any given length of time but although it's been a while since I have had to do any calculus it is possible, in fact, to calculate precisely the % change.

The % of water changed each day goes down a little bit each day and the change in that difference between day x and day x+1 also decreases with time (Static Change (drain and fill) = 30 % every day vs. Dynamic Change (Drip) Day 1 = 25.9 %, Day 2 = 25.?4? %, Day 3 = 25.?2? %, etc.) That suggests a rate of change that approaches a limit. The time it takes to reach the limit depends upon the drip rate and the rate of absorbsion. That limit will be the % change when the system reaches equilibrium and can be found with differential calculus with a high degree of precision (limited by how many decimal places you want to go to.)

My guess is that the limit reached would be close to 25 gal. a day and the amount between day 1 and eventual equilibrium is trivial.

Of course, it's been a looong time since I had to do any calculus!

Scott

[scans]

BTW... here is the tank pic I promised a while ago !!!

[sleonard]

Sweet!