Filtration rates, flow, and other questions

Nice Shibby! Now it makes sense... a picture's worth etc
Not going to work for me though as I'm not willing to upset my existing setup with planted substrate to make a hole in the bottom of the tank, but nice idea if one is starting from scrath with a new setup.

 

SHiBBY, if you must design a new tank, will you do it again, or go with the prof's design?

 

I'll always use the overflow design I've currently got. It's easy to maintain, introduces oxygen into the water, and is simple yet effective. Another similar design is to build a 45 degree overflow instead of the box shape. If you do the same in opposite corners of the tank, one is used as an overflow and the other as an inlet. I've seen it and it looks and works awesome! When both is at a 45 degree angle, they create an effective surface current that "feeds" the overflow. That's what I'm going to do with my 2m tank later this year!

 

shibby, i suggest you look into a slimline overflow, couple of tanks on masa has it.

 

Thanks, I know about the slimline overflow. Friend of mine is the owner of a certain marine LFS in Centurion. ;-)

 

Hi Prof @Dirk Bellstedt and everyone else

Just noticed that the diagram for Prof's design requires 5mm glass for the sump. Is this to take the weight of the gravel in the filter section? I was hoping to convert an empty 60cm tank to this design sump by it's glass is only 3mm thick. Will it hold or do I need to start from scratch with 5mm glass? If I can use the 60cm tank as a sump, wil 3mm glass be ok for the partitions inside or must that at least be 5mm?

Also, the 2ft tank to be converted to sump is 315mm wide x 300mm deep. That is shallower and wider than Prof's design. Will this be a problem? Wider I guess is good as more filtration area but will there be enough gravity flow with the shallower depth?

Oh, one more thing, I built the overflow pipe as per the other diagram with the double U-bend. Works but flow is VERY slow. I used 20mm PVC pipes - is that too thin?

Thanks
Neville

 

Hi Neville,

The thickness of the glass for any aquarium including my filter is determined by the depth of the aquarium. My sump is 50 cm deep and therefore 5 mm would be viewed to be the minimum glass thickness. If the aquarium that you want to use for your sump is not so deep then the glass can be thinner. So the thickness has nothing to do with the weight of the gravel, this would be just as heavy as the water in any case.

If your sump is shallower and wider this is not a problem. Wider is advantageous because of the surface of the filter area, you are right there. However, if it is shallower the total volume is also reduced so this is a disadvantage again.

20 mm PVC for the down pipes is too thin yes and will restrict the flow.

Kind regardsm

Dirk

 

Thanks for the prompt response Prof @Dirk Bellstedt

What size piping do you suggest then? The tank to be filtered is only a 2ft tank (as the sump is) but slightly deeper at 32cm instead of 30cm. Yes, I know it seems overkill but its really an experiement with sumps and "they" say "one can never have too much filtration". ;-)
There weren't many piping systems at my local hardware store, besides the really big stuff used for toilets, that come with U-bends already made. Hence I bought a pipe bender and made the bends myself. Figured this would also save me buying joins. I suspect though that the rinkels I got in my bends, not being experienced a this, might also be hampering the flow rate.
What piping did you use?
And re. the gravel, can I use an old mixture of silica and pea gravel as the filter media? The silica is about 2-3mm in size with a little bit of coral chips in. (I previously used the coral chips to try and stabilise the low PH of the Cape Town water.)


My first attempt at the syphon system for sump...

 

@Neville
Wow man! Neat!
How did you do the nipple for the air pipe?

Did you heat the pipe a bit when you used the pipe bender? The wrinkles is a little bit big, but about normal for a pipe bender. I get them a little bit smaller when I heat the pipe with a flame, but it is tricky, if you do not do it every day.

Sorry to butt in, but if you say 'slow', does it throw a full 20mm flow, or is it doing like half or less of the pipe's capacity? Also, 20mm is standard electrical pipe (conduit) and there is a lot of bends and connections available at electrical suppliers to the building trade. That is if you want to miniaturise or get it 'tighter' to save space. You also get it in 32mm.

 

HI Neville,

For a tank of this size, you do not need such a high flow rate, so the 20 mm PVC pipe should be ok. I also cannot see anything wrong with you syphon. I think that the powerhead that you are using is too strong.

The gravel mixture should be fine, but if the flow rate is not enough then this will be the cause of the problem. You will just have to experiment to get the fine tuning right.

However, I think all is ok.

Kind regards,

Dirk

 

Thanks Prof @Dirk Bellstedt, I shall persist then BTW, I haven't built the sump yet as I was unsure of the glass thickness. So to test the syphon I simply used two large backets. So there was no actual filter media the water was running through in my "pretend"-sump bucket. The flow is about half of the pipe diameter hence I'm worried its a bit low. I thought of having the down-pipe out of the water on the sump side to increase downward flow as it doesn't have to "push" against the pressure of the sump water, but then as you prevously siad, when the power goes out the pump stops, the syphon will be broken.

@Tom.K, thanks or the thumbs up. Yes, I did heat the pipes over a candle. It worked well but as you say, took some time. The top bend's ripples are much larger and somehow I got the bottom bend smoother. I think it has to do with how hot you make it, e.g. if you heat it a lot and do the bend in one go you get the ripples. Whereas if you do it slowly a bit ata time, it is smoother... I think... or perhaps the other way around...
The nipple is from a used airstone. Sometimes when changing airstone piping I pull the stone part off its nipple as the stone seems to go soft and brittle over time. I've kept some of these as I thought it might be useful for something in the future, and I'm a store-rat in general. A 5mm drill makes just the right size hole for the thick end (previously inside the airstone) of the nipple to fit into the pipe. Sealed it off with some silicon on the outside.

 

One very important thing:

Don't seal PVC with silicon as it does not stick to it at all, use PVC glue and only that. The airstone pipes are PVC, so this should be fine, but don't use this overflow before you reseal with PVC glue or you have a potential disaster on your hands.

Kind regards,

Dirk

 

There you go. Great!

Prof, while you are here, what would the method be to work out the ideal flow rate through the sump? So that the flow rate is not too fast, nor too slow?

hehe, hope it was not already discussed in the previous 150 posts, as I am then going to get my butt kicked again ;-) Neville, you recently read the whole thing, help me out please!

 

@Tom.K, yes these are conduit pipes. They assured me the blue pipes are more suitable to water and are thicker than the usual white ones too. They do have bigger sizes and I could experiement with that. 2m of 20mm pipe cost me under R8. The bender was R40. Yes, there were lots of connecters for the electrical stuff but only 90 degree elbow bends that are solid. The U-bends have an open plate at the back with screws intended for maintenance of the wires. Even if I silicon this lot up it will be messy and ugly. The grey T-piece you see in my pic, is nice as it fits over the outside of the pipes, thus not makeing the inner circumference smaller and also require no glueing.

 

I also forgot about that! Thanks Prof. And of course let it dry properly so it is not poisonous to your tank.

 

Btw gents, where do I get the perforated perspex for the bottom of the sump?
I'm guessing by perforated Prof means "drilled with lots of little holes"?
What else would work? It will ahve to hold the weight of the gravel...

 

The PVC weld Prof. is talking about is very thin, like water and not messy at all. Nothing wrong with what you did, as I said, it looks great. Just to get it smaller, I will join 2 90's with a piece of pipe inbetween, that does not make the join longer. That should be small and tight. The 90's goes over the pipe, not? So it does not make the inner diameter smaller?

 

Hey Tom, will have to go look at the elbow joins agian but I suspect two of them won't make the bend smaller, not by much any way. I thought of this in the shop but then thought that water will flow easier through two U-bends than through 4 90 degree elbow bends. I think the 90 degree bends ar emore restrictive but I might be nitpicking now.

 

Neville,

buy a piece of perspex and get out the old drill, my china.....

Tom,

I am going to kick your butt, we discussed the flow rate thing to alsolute stone dead depth, so I am not going there again...

Kind regards,

Dirk

 

lol,:bigsmile: I suspected as much, but only remember it must be slow, but not too slow and do not restrict the flow with up and down's. I do not recall a calculation... So Neville, it is up to you bro, whereabout is those posts?:wondering: