Which type of water movement?

[James O]

I'm looking at a 300-360l tank that's between 180-200cm long. Substrate will be planted with 2/3 groups of cryps and Echinodorus ie not much. Most of the plants I intend to place between rocks and on wood. Swimmers will be rainbows. I use flourish & excel but plan to go onto Gluta-whathisname due to the tank size

I'm pretty set that the Filter will draw from one end and output at the other but I'm not sure on flow. I could have a couple of powerheads blowing towards the inflow. Or I could use a pump attached to a full length spraybar for a cyclical movement.

What do you think based on my looooooong tank?

 

[Julian]

have everything pointing in the same direction, with your outflow point towards the front of the glass running horizontally across the top of the water. Gravity will do the rest.

 

[James O]

Tnx Julian.

Filtration aside, which of the two choices (open to any more) will best move ferts & excel over plants for growth and algae reduction?

 

[Julian]

Well, you can't really control where your ferts land, it all gets absorbed into the water so I wouldn't worry about it. If you're getting more than a few random spots of algae, it means you need to turn the lights down. Trying to control it with ferts (depending on algae type) will do little.

 

[James O]

I take it you don't subscribe to the 10x theory then?

 

[Sacha]

I have 24x flow in my 125 litre. If I had the choice, I would have even more. Maybe 30x.

 

[James O]

Exactly! 10x movement is not for filtration, its to ensure adequate movement of the water column containing the fert/CO2 and ideally to ensure no dead spots. Algae doesn't like heathy growing plants and movement -OTOH it loves weak plants and dead spots. If you had adequate ferts/CO2 but no movement you would have to reduce your light. Improve movement and the light can be properly harnessed by the plants in conjunction with ferts/CO2 it is now receiving.

So in a long 200cm tank thats is pretty much square in section, what style of movement would you suggest Sasha? Linear (end to end) or cyclical (or other alternative)?

 

[Sacha]

A long spray bar along the back of the tank, pointing towards the front glass and very slightly downwards. Then maybe a Hydor Koralia to deal with any spots the spray bar can't get to.

 

[James O]

Belt, braces, hat & coat! I like your style 😀

As I'm using wood that could break up the cyclical flow of a spray bar, the koralia could be employed to mix up that central area.

Would this work better than just koralia alone?

 

[Julian]

I don't think there's one type of rule you can employ in every single tank out there. For instance, a tank with just substrate isn't going to need as much water movement as one with lots of hard scape. You have to look at your tank and read what it's telling you - look for dead spots where plant growth isn't moving etc. I like my plants to all have a gentle sway, this way I know there is a current passing over them.

 

[James O]

I don't think there's one type of rule you can employ in every single tank out there.

I've only mentioned and am only interested in one tank (Please note the first paragraph of first post at top of the page)