Using a dosing pump to do water changes? - That's an interesting idea.
Presumably the level is governed simply by an overflow?
What percentage of your new water ends up going 'straight' out the overflow in a given 24 hour period I wonder.
I am putting an overflow bulkhead in the back corner of my new tank, the idea being that I just pump new water in and let old water overflow out through the bulkhead - but was moving away from that idea as was thinking that too much 'new' water would end up going straight out the overflow.
Was thinking about putting a 'T' junction and stop taps on the lily pipe inlet:
- Switch off filter,
- reverse taps, pump new water in through lily pipe,
- then switch taps back and restart filter.
Yea it's a height setting overflow with a shrimp safe mesh cover. Also allows for floating plant/leaves clogging etc.
With the dosing pump I'm dripping directly to a high flow area, so I'm fairly confident the water is mixing fully.
Mathematically it's definitely removing some of the new water while it gets added, but the proportion isn't high.
Adding say 3lt to the system volume of say 60lt, it's 5% added.
You remove 5% (the maths is actually slightly more technical but it's close) of the new, 95% old.
Of 5lt removed you are removing 4.75 old, 0.25lt new.
So 5% less efficient that remove then add, but also much easier therefore going to always get done and will continue when I'm away on the rigs etc.
Stability being the key.