Sump - over/underflow capacity

[JoelB]

Say I have a plain vanilla wet/dry sump with two equally wide chambers made from a small tank. One chamber is for filter media and the other is the pump collection area. The baffle coming up from the bottom goes up half way so the normal water level for the bio media is half way up the sump, and the normal capacity for the collection area is one quarter of the sump capacity.

Let's say that with evaporation the collection chamber can drop to half of its normal level before the pump begins to get uncovered, leaving one-eighth of the tanks capacity as lee-way for evaporation before I have to top it up.

1. Is this true that with, say, a 20 gal sump I would then only have 2.5 gal of evaporation before I put the pump and filtration at risk?

2. Is the 5 gal of air above the collection chamber wasted capacity? I mean, if I flood the normally half dry bio media, will I upset the BB? and what would have been the point of the baffle if I did?

 

[chesterthehero]

1- correct.. i think.. i suck at math but it sounds right to me..

2- is the media dry? if so then yes its being wasted... if its being driped on (wet but not submerged) then this is good some BB grow better when being driped on just as some grow better when submerged...

 

[JoelB]

2- is the media dry? if so then yes its being wasted... if its being driped on (wet but not submerged) then this is good some BB grow better when being driped on just as some grow better when submerged...

I'm talking about the dripped on bio media getting temporarily flooded for capacity reasons or while I'm doing water changes or whatever.


I'm starting to think that for a 130 gal tank, this little sump idea needs a bigger container. Or is there a better idea?

I really wanted the sump to be a glorified hang on back filter that doesn't hang on the back and that gives me a better way to do water changes and to hide my heater etc. etc.

 

[chesterthehero]

i flood my sump durring water changes... ive yet to have any issues.. all depends on how long you flood it for.. i dont think its so much an issue of flooding the media as it is leaving it flooded and the BB running out of food and dying

general "ideal" sizing for a sump is like 1/4-1/3 or something like that.. and 3-8x turnover... but at the same time all depends on yer stock and bioload