Fluval FX Spray Bar

[Dork Fish]

I picked up a Fluval spray bar for a FX4 filter, The spray bar comes in 3 sections but only 2 fit in a 75 gallon.

When only 2 of the 3 sections are used, the spray bar extends only 2/3 of the tank.

Should a spray bar extend across the entire back of a tank, or is it only supposed to only extend 2/3 of the tank?

I can always cut the 3rd section down to fit the tank if needed. Just want to make sure before I permanently modify the spray bar. 🙂

[mynameisnobody]

The less sections, the higher the pressure. Using 2/3 and you will be fine. Using 1/3 is a bad idea unless you want a really high flow. 

[Dork Fish]

@mynameisnobody Thank you, I am aiming for the flow to be as low as possible and for max surface agitation. Had debated cutting the last section to length in order to get as close to the length of the tank as possible. Just not sure if there is a general guideline to length of spray bars. 🙂

 

[Colu]

I would cut it so it fits the full length of the tank if you want more surface agitation as a rule the shorter the spray bar more flow 

[anewbie]

There is no right answer here - it depends on your tank and the fishes you have. Some fishes find current intolerable - the other the more the merrier - only you can determine if you need the current to cover the entire top or if you need less current in certain areas.

[Dork Fish]

@anewbie I am sure that I want less flow and more surface agitation. I have never owned a spray bar, so I was just checking here to make sure there was not any negative impacts of having the entire length of the tank affected by a spray bar. 🙂

My thinking was that Fluval may have made the sections of the bar odd lengths on purpose.

Looks like that is not the case though, which is good for me. I am just going to cut the 3rd bar to length.

[nabokovfan87]

On 6/27/2023 at 9:03 AM, Dork Fish said:

Should a spray bar extend across the entire back of a tank, or is it only supposed to only extend 2/3 of the tank?

I can always cut the 3rd section down to fit the tank if needed. Just want to make sure before I permanently modify the spray bar. 🙂

I ended up cutting mine.  Getting full flow across the length of the tank is what you want for something like CO2 dosing. If you're just using it for general movement, I wouldn't bother cutting it. 

[Pepere]

I like it full width myself.  I cut mine to fit…

 

if you cut it, make sure you dont cut off the end that has a plug in it.

and I dont think I would worry about flow being to slow.

And while the pressure coming out the individual holes will be more with shorter sections, the higher pressure in the flow bar is contributing to higher back pressure over all and less flow overall…

 

In essence your pump starts with a certain feet of head potential.  All of the media you fit in the canister and flow restriction from your piping eats in to that head potential reducing the flow you experience overall…

Full length will give greater overall flow, and reduced velocity out of individual holes in the bar…

 

I seriously doubt you will be dissapointed with the surface agitation from full width…

 

worst case, you can take the shortest section out if you wish to try it shorter…

[Dork Fish]

@nabokovfan87 Yeah for me it is mostly because a betta is going in the tank; however, I definitely want to get into CO2 dosing at some point down the line.

@Pepere Your point about the backpressure causing less overall flow is compelling. I had not considered that.

Well that settles it then. Will definitely cut to fit 🙂

Now to figure out my lava rock questions LOL:

My other forum post