Planning my sump.

syphon overflow will lead to flood, maybe it will take a month or a couple of years but syphons is not 100% fail safe, you can only get 100% fail save if you have a drilled tank and an overflow that works with gravity. One example is the build up of micro bubbles in a syphon overflow, which could lead to a complete syphon break over time.

 

+1
I also would rather recommend a skinny overflow...

 

No, it can not suck your tank empty. You do not understand the working of this overflow. You never ever break the siphon, unless you are present and do it intentionally, for some reason. Then you would cut power to your pump as well. The overflow drain your tank to the lowest level in the T junction, then it stops automatically. Once the level in the tank rise higher than the lowest level in the t, the water starts flowing again, like MAGIC ! hehe...

 

Please explain what you mean by this? Your overflow intake is nowhere close to bubbles. Also understand that this is not a siphon in the traditional sense of the word. It is more like your toilet, but upside down.

Edit: Also see the design of the overflow intake. The intake is via holes on the side, with a solid cap at the bottom. Bubbles can not turn a corner and enter from the side. The suction is relatively very week, because of the area around the pipe.

 

It's just a precaution that is used in almost every single marine set-up I have ever seen.
If the power goes out while you are away from home the return pipe from the pump back to the tank is filed with water and that water gets sucked (Pulled by gravity) back into your Sump if the pump is not running and pushing water to the tank .
This situation obviously depends on how deep your return line goes into your tank, if the outlet is 1cm under water on the return line you don't have a problem (eg: a spry bar) but if you would like it to spry the water back into the tank at a deeper level say half way down this could suck your tank half way empty, This happened to so many marine keepers in the past this is why they all have the 2 little holes on the return line right under the water level.

This has nothing to do with the siphon of the overflow. Once the water hits the sump and flows through the sump the siphon part stops and the Return pump starts. A return pump can have water flowing backwards with enough gravity. Unless it has a one way flow valve type thing.

Also Micro Bubbles are everywhere in water.
Fish and plants can't live without micro bubbles, it's how they breath.
Not bubbles from an air-stone but bubbles that are caused by water movement. and I'm sure this build-up will take a long while before it has any effect but eventually it will unless you make sure it doesn't.
U know like the small tiny little bubbles you get on your skin in the bathtub.

 

Well i still have to put all the glass peices in to the "sump" so i want to know what would give me the best filtering? down, up, down and pump out route, or a straight through 'big bore' flow?

 

The down up down will have more head-loss (Not much) coz it works with and against gravity I'd say

 

You are right and I stand corrected. My return is 1 cm under water for this reason. I thought you meant the other side.

As far as the micro bubbles is concerned, I am not worried. This will take a very very long time, especially as the opening underneath is solid. You are bound to work on the overflow before that happens and reset it when working on it.

 

I believe in the straight through method. Did you read Profs thread about the 'big bore' principle? I gave a link earlier on for you to read. The massive long thread.

 

lol I figured there was a miscommunication there, :blink:
My bad first post didn't say "Return line" anywhere.

 

thats how the up down up down thing works right?

 

Jip. RFS will be able to point out more how it works. What I have against it, is it increase the velocity of the water in the sump, rushing through your media. The straight through method slow the velocity down and the media and bacteria does a better job. Your water must just be oxygen rich.

See my earlier posts about the dividers. You do not have to go that fancy. Use anything practical to keep the media separate and do not obstruct the flow of water.

 

There is no space for a DSB in there, And that would cause a loss of oxygen (Not such a bad thing)
U'll need to put an air stone in your return chamber...

 

I would also rather go for the straight through.

 

OK and straight through is how?
Yous guys must be getting sick of my 101 questions! Just really want to get it perfect!

 

Like TomK's one.
Mesh type panels instead of compartments, you could maybe use egg crates for this if you don't know someone with a laser cutter or have enough patience to drill all those little holes.

 

Anything like this. Plastic, so it does not oxidise.

I must admit, it is a bit of a challenge if you do not want to spend, like I did. It cost me about R60 per Perspex panel and a further R70 to cut the holes per panel. Or you could find a stiff plastic sheet, cut to size and drill full of holes? The plastic mesh stuff you get in nursery shops is too flimsy. I tried it.

 

U can get egg crates from Dorry's I think, should do the trick just you might have to buy some under gravel mesh/floss stuff (Those flat floss sheets you put on a UGF) to keep your media in their compartments coz an egg crate will probably mix your media due to the huge holes.

Also Check out Maizey Plastics for something that is already full of holes.

 

What is the dimensions you are going for on the sump and Glass thickness?
And how many times do you want to circulate per hour ?

 

@TomK i agree that the flow speeds up, but the water travels a longer path through the media with the up down method.