FX5 Spraybar Troubles...

[scifisarah]

So I made a spray bar for my FX5 on 75 gallon tank and have not been able to get this simple concept to work for me. No matter how I set up the holes, too much pressure comes out the last few holes of the bar and blasts my Tahitian Moon sand off the bottom and flings it into the filter intake. I have tried all small holes, large holes going to small holes, small holes going to large holes, all huge holes and nothing will work. More current always comes out the last foot of pipe and blasts the sand there until the bottom of the tank is down to the glass. I am using 3/4 ID and the OD is about 1 1/16". It is 34" long and holes are spaced in an even line 1" apart. The end is capped and it is held on my suction cups. I aim it slightly upwards so it creates surface agitation. Below is a photo of my first attempt of all smallish holes - sorry for the bad reflection! Any ideas on how I can get more even pressure, and not have the sand blasted from the bottom?

[Marty]

It sounds like the filter is pumping too much water for your spray bar to handle.  Here are some possible solutions:

Try to drill more holes and make the spray bar a little longer as well.

Install a Y connector with one half going to the spray bar and the other going to a standard output for a FX 5.  You may need a ball valve to adjust the pressure to the standard output to ensure you still get pressure to the spray bar.

Install a ball valve in the output line to reduce the pressure (I'm not sure what effect this will have on your pump, though).

[scifisarah]

When there is lots of pressure coming out the end of the spray bar, I should also mention there is also very poor pressure for the first foot of the bar. I just don't understand how even pressure can be achieved, but I see lots of people doing it successfully with FX5's on 75 and 90 gallon tanks on forums, youtubes etc. Could it have anything to do with the thickness of the pipe wall? I know my biology but am pretty weak when it comes to physics and engineering. I would like to stay with one length of pipe, but might end up getting a T joint in the middle of the tank and having 20" spraybars come out of that to possibly distribute the flow more.

[NorthernAquatic]

I think you may need a smaller I.D. pipe.

[theoryguru]

I'm currently running a 48" long spraybar of 3/4" PVC in the same position as yours in my 125g.
Holes are about 1.5" apart and I used a step drill and made 1/2" holes.  I used Krylon camo black and it blends well into the 3D bg.  Overall the output is fine, besides surface agitation, I wanted to change the water flow for my fish to swim in.

Despite the performance, your spraybar looks great.
You do have a lot of holes so I can imagine the output is high. 
Without making a new spraybar, I would first start by make every other hole larger to 1/2". 
Install and see if that works, if not then start by enlarging the half of the holes to 1/2" starting at the end furthest from the connection.  If that fails then make a new spraybar with 1/2" holes 2" apart, your length looks good.     
I've read about ppl adjusting the output at the valve to about 80%, although I decided to maintain full flow and tweak my spraybars instead.

My first spraybar was 15", 3/4" PVC positioned at the top of one side of the tank.  Its length made it a high output spraybar, but my fish didn't seem to mind and I liked that it was almost completely out of view and used it for over year without issue.

I've made several (and constantly experimenting) spraybars for my FX5s...
Lots of trial and error.  Good luck and keep us posted.

.. my daughter enjoys Dinosaur Train too 

[Marty]

How about using a reducer coupling midway with a smaller diameter pipe at the end?

[mightieskeeper]

I would make a t with no holes the 1st foot.  Then drill lots of really small holes.  I made a spray bar for my 50 gallon years ago.  I had the same problem kicking sand up.  I had a ball valve to slow my pump down too.

[Ron]

I think you may need a smaller I.D. pipe.

That seems opposite what I think would help. Based on my experiences with modifying cars, it's easier to maintain a high pressure with a smaller line, but it limits flow volume. Going to a larger line allows more volume and conversely can make it harder to maintain pressure.

I would make a t with no holes the 1st foot.  Then drill lots of really small holes.  I made a spray bar for my 50 gallon years ago.  I had the same problem kicking sand up.  I had a ball valve to slow my pump down too.

I think that would get the desired results, but would put a lot of back pressure on the pump similar to using a ball valve to regulate flow.

2 solutions that I see...

One, you could split the output between a spray bar and the standard output as Marty suggested, using a ball valve to regulate flow out of the standard output, putting just enough pressure on the spray bar to make it work.

The second option would be to first insure the spray bar is tilted up enough for good surface agitation. Then start enlarging the holes and retesting until you've made them large enough that they still ripple the surface well, but don't stir up the sand. The size of the holes might be surprisingly large since that is a big filter IIRC (I never used one myself).

[scifisarah]

I will have to think about it for a while. Right now I just have the old out back on and will have to look at all the poop on the bottom until I do weekly water change. Amazing how quickly it collects without the water spinning! I have the ability to decrease the flow on my fx5, but to get the end of the pipe to not kick up sand, I would have to reduce the flow so much that the first half of the spray bar is trickling out slowly. All the poop then settles on the right side of the tank and does not go into the filter which is my main reason for the spraybar in the first place. I've angled it upwards a lot and the water still hits the front glass eventually and goes down to kick up the sand. That particular bar is screwed up with huge holes now, but I have enough pipe to make one more bar. All really large holes still resulted in the water shooting down to the end and coming out the last few holes. Basically whenever the water meets resistance, it shoots out the holes right above that really hard, whether than is the end of the pipe, or my attempt of putting all large holes at the front of the pipe and small holes at the end. I think I will look at the pipes the next time I am at Lowe's and see if they have any with thinner walls to see if that is part of the problem. I wonder if the hose sides are so thick, that it is easier for the water to shoot by them to the end, than the energy it would take to turn the corner and go out the first holes on the bar. Adding the old outtake with a ball joint w/spraybar might work, but I'd worry about having the same uneven pressure problem with the spraybar. Even when there was more than enough hole surface area in the bar, all the water would just shoot out the holes at the end, with barely any flow in the first half of the bar. Very irritated about not being able to figure this out.  Thank you for all your suggestions, I will take them into account when puzzling this out and let you know if I ever get it fixed.

[GrizzlysDad]

I see lots of people doing it successfully with FX5's on 75 and 90 gallon tanks on forums, youtubes etc.

Have you tried asking on those forums where the people have achieved the proper result?

[scifisarah]

I see lots of people doing it successfully with FX5's on 75 and 90 gallon tanks on forums, youtubes etc.

Have you tried asking on those forums where the people have achieved the proper result?

I have but I was hoping to design mine more simply than some of those, without having the joints that go over the back of the tank but I think that may be part of my problem. Instead of encountering corners, the water shoots horizontally out of my hose into the bar. Great for flow, but perhaps it just needs to be slowed down by turning some corners first. I will probably build directly from someone else's plans instead of trying to avoid using joints on my next attempt. Better not to reinvent the wheel.

[VWalker]

For my FX5 spraybar, I went with a 40" spray bar that has 38 holes drilled with a 3/16" bit spaced every 1". As far as positioning, mine is similar. For a reference of exactly how mine is set up here's a link.

greatlakesaquaria.com/index.php?/topic/3022-diy-spray-bar-for-fx5-filter/

[theoryguru]

Not a great pic, but this is my 15", 3/4" PVC bar that sprays left to right at the top of my tank. 
You can see where I enlarged the (white) holes to 1/2".



And here's the 48" bar, the holes are the same 1/2" spaced about 3-4" apart.
I haven't had any issues with it moving the sand.

[Maize-N-Blue-D]

Sarah - have you figured out the spraybar issue yet ?   Also is that a DYI background on your aquarium?  if so very nice....

[scifisarah]

Sarah - have you figured out the spraybar issue yet ?   Also is that a DYI background on your aquarium?  if so very nice....

I did get it figured out, and no unfortunately that is not my lovely background! I was going to get new schedule 40 pvc and figured what the heck, I have two more "tries" worth of schedule 80 sitting in my basement so I sawed two more lengths and thought about it a bit, based on the comments on this forum and another. For my first design, I had read somewhere that bigger holes = less pressure because it was not forced through such a small hole, so I made them all equal sizes at first, then when there was lots of pressure in the last foot of pipe, I made those holes bigger to try to make the pressure less direct. BIG MISTAKE What worked is actually the complete opposite. When I made the holes at the end bigger, there was less resistance there and the water just skipped over the first two feet of pipe and blasted out the end. I tried turning the pipe around, but by then, all my holes were really too big to be useful.

This time I started out with really small holes in two rows. The top row I made a bit bigger as I wanted that to be my main area of pressure. from the capped end of the pipe I started making the holes slightly larger every other hole and spaced them 2" apart. To lessen the pressure a little, distribute the flow and not create too much pressure on the filter, I also included a second row of smaller holes beneath the first row that would shoot out slightly downwards. Because they are small compared to the holes above them, the current coming out of them is not very strong in comparison.

I included some photos, and moved the light over it so you can see how it is set up and how it connects to the end. Like I said, I was hoping to do this as simple as possible without buying al the extra joints. There is no sand blasting now, and the flow is more evenly distributed and breaks up the surface well. If I had even a slightly larger tank, say a 90 gallon instead of a shorter 75 gallon, or the length of a 125 so the water has somewhere else to go before hitting a glass corner, I do not think the blasting sand would be an issue. But since it is such a high flow filter for this size tank it seems to take a bit more guesswork. And YES we are watching Dinosaur Train, AGAIN.