Will this work? Trickle filter / sump / automatic water changer

[Chris McMahon]

Here's a design I've made for a trickle filter / sump / automatic water changer.

My tank is a 5x2x2 (470 litres / 122 gallons) that I'm setting up as a planted discus tank.

http://users.bigpond.net.au/darkcity/sump.jpg
It will be set up to change around 10% (48 litres) per day, but can be increased just by using a larger dripper (20% with 4l/hr etc).

So long as the pump capacity at 1.2 meters head is less than the return 25mm hose's gravity feed capacity (2500l/hr?), the main tank's level should remain constant. The 25mm waste bulkhead in the sump should also limit the water height in the sump to around 16-17cm, even in a power outage.

I'll be running a in-line 5 micron water filter on the inlet water dripper which should take care of the chlorine (no chloramine here).

I'll need to watch my GH and KH levels. With a PH of 6.5, 36ppm KH should give ~19PPM CO2.

My PH should be taken care of by my automatic CO2 PH controller controlling a Co2 tank with reactor (installed after the return sump pump).

Thoughts? Feedback? Am I missing anything?

[stygian7]

I use a float valve in mine. It's unlikely, especially in a post filter setup, but if your drain gets pluged and you're out of town, you could have a mess. Maybe I'm paranoid, but I'm in Mexico for a month over Christmas and only have someone coming by every few days. With my system, I'd potentially have 50-80 gallons of water on the floor before the problem was noticed.

[Chris McMahon]

I use a float valve in mine. It's unlikely, especially in a post filter setup, but if your drain gets plugged and you're out of town, you could have a mess. Thanks, a valid point.

As I see it, there are two possible points of failure that could lead to flooding:
1) The gravity outlet of the main tank blocking - causing the sump pump to gradually overflow the main tank.
2) The sump drain blocking (as you pointed out) causing the sump to overflow.

Of the two, I'd say the first is more likely as the sump drain is post filter.

As for solutions, situation 2) can be solved by a float value, the effect would be no water change until fixed - nothing too dramatic.

As for situation 1), maybe a float switch in the main tank relayed to the sump pump? The result would be no trickle filter or water change of the main tank. A more serious situation than 2), that would have a lot less safety time for resolution. Perhaps before long absences a backup internal filter could be placed in the main tank?

I don't plan on taking any long trips, but planning for failure is definitely a good idea. Thanks.

[Chris McMahon]

Last call for comments. I'll be getting this thing built soon and then it'll be to late to change anything.