Trying to improve flow / circulation

[humdingerx]

My tank is 4 foot long and I am having some issues with circulation I think. My set up is currently like this:



The spray bar is pointing forward towards the front of the tank. It is not full length of the tank unfortunately and is attached to filter output (top right) with an curved "L" bend in the pipe. Intake is on the left.

I noticed the plants to the right of the spray bar are not moving, which indicates no/poor circulation on that side (marked by X's)

Also to the left of the intake and along the bottom/left side.

Middle of tank is fine as can see plants near the substrate swaying gently.

I'd like to know how I can improve this set up? Currently CO2 diffuser is on the left side too so I don't think I'm getting decent distribution of that either.

I was thinking:

1) remove the spray bar completely and put back in the default filter sheppards hook type of outlet, have that pointing diagonally across the top of the tank to the front/top/left corner

2) move the filter inlet to the same side as the outlet

3) leave the co2 diffuser where it is on opposite side of tank.

Idea being this might create a circular flow pattern across the entire tank? Ideas?

 

[Rahms]

assuming your filter is providing enough turnover, extending the spray bar can only help

I think the biggest single change you can make will be an inline diffuser. 4ft is a long way for the co2 to disperse, especially considering the flow is transverse

 

[humdingerx]

Sorry I forgot to mention it's a Fluval 405 filter. That should be ok for 200 litre tank? I could extend the spray bar to the left which will help everything on that side but still have this problem to the right of it having quite poor circulation. I can't really shift the bar more to the right because the cutout in the lid of the tank won't let me move the pipe further along.

I was thinking might have to go inline, but want to see if any other options before that 🙂

 

[tim]

Fluval 405 is probably lacking in flow to run a full length spray bar, consider supplementing with powerheads to increase flow and eliminate dead spots.

 

[Fran]

Hi, you are definately going to have dead spots with your current set up. Ideally, you may want to add a second filter and use them to run two foot of spray bars each. You would have to go inline and split the co2 flow which would mean 2 of everything i.e. diffusers, bubble counters etc. All of this would be hard on your pocket of course. I had similiar isues on a 5 foot and found this to be the only option that worked for me. Perhaps you could go with the shepards hook inflow and get hold of a powerful powerhead to blast the co2 around your tank either with an inline or in tank diffuser. This may be the cheaper and more workable solution. Best of luck.

 

[Fran]

Also, bear in mind that your filter is rated at 1200lph (I think) and ideally you should be aiming for about ten times your volume i.e 2000lph hence the need for a second filter. Cheers.

 

[Rahms]

regardless of how strong your flow is, its not in the direction your co2 has to disperse. ie flow from back to front, but you want your co2 to travel 4ft left to right as well.

imagine a diffuser in a stagnant tank, bad right? Well your left to right flow is probably not much better

 

[humdingerx]

Thanks for all the help 🙂 Looks like a few issues then. I've a spare powerhead (maybe two need to check) which will help short term. Can try that with the sheppard hook and see if that works any better. Still have to do something about that dead zone to the right.

Might have to look at a better filter and diffuser to help reduce the clutter. Any recommendations? I'd prefer if I could to keep to one filter that could drive maybe a spray bar for the whole tank? or is that not really possible?

 

[Andy Thurston]

I'd prefer if I could to keep to one filter that could drive maybe a spray bar for the whole tank? or is that not really possible?

possible but more expensive than adding another smaller filter or powerhead

 

[humdingerx]

I actually have a spare diffuser so could probably split the CO2 - just need to buy another bubble counter (or make one easy enough with a bottle) and needle valve. So that wouldn't be a problem to do that bit. Then it's a case of sorting out circulation, as I already have a spare powerhead or two could try that first. It'll be next week before I get time to reconfigure in any case, I'll add the powerhead in somewhere in the meantime to get some water moving around that right hand side.