Whistling pipes

naughtymoose

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My two Fluval 306 filters each feed a Fluval spray bar.

There is one joint in each of the pipes leading to each bar (in preparation for CO2 in-line diffusers, if it ever happens!)

Ends of the spray bars had to be super-glued, as they kept shooting off.

Each 306 is cranked down to approx halfway flow as if they are opened any more there is an irritating whistle coming from the pipes.

Other than turning down the flow as I have, can anyone offer any anti-whistling solutions?
 

ian_m

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Loads of things you can try, this has been seen numerous times. Pipes resonating due to fluid flow is very common in industry. Generally sorted by damping in some form or other to stop the pipes resonating.

- Wrap elastic bands round the pipe at various positions.
- Try covering up, using insulation tape, one or two of the holes, maybe at positions 3 & 7. (basically a prime number).
- Place the holes with slightly different gaps between them if you make your own spray bar.
- Widen some of the holes.
- Put a tiny hole at end of pipe.
- Join the two sections with a short length of flexible PVC pipe.
- Extend the end a couple cm using flexible PVC pipe.
 

humdingerx

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I had exact same issue with my old tank, which was also a 306 filter with fluval spray bar. How far down in the water is your spray bar? I found the whistling noise seemed to come from the white (maybe light grey) rubber bit which connects the hose to the spray bar - especially if the L bend is a tight fit and could be stretching the lip of the join as well.

I got around it by basically submerging the spray bar further down so the white rubber connector was completely submerged and then angled the spray bar up a bit to get surface agitation.

I've since moved to a fluval 405 but with the same spray bar and new tank, and not had the whistling noise. Possibly because the L bend isn't so severe/jammed up against the glass in my new tank...
 

naughtymoose

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Mmm. Thanks for that hum.

I chopped the rubbery bit off, as it stuck out like a sore thumb. Each of the filters has only one of the two supplied bars. I'll try a couple of Ian's suggestions and also look at the angle of the supply hose, as you suggest.

I'll do the hole in the end thing and also widen some of the holes.
 

humdingerx

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Before cutting permanent holes trying putting the spray bar in "loose" if you can i.e. just dangling submerged and with the hose end straight(ish) see if that eliminates the whistling. If it does then that might be a clue.

Edit: I just looked at your tank in your signature link. The "L" bends to the bars don't look too severe to me. Mine was almost 90 degrees and jammed right up against the glass, which caused there to be a small gap with the rubber lip which was probably sucking in a tiny amount of air or something. So more than likely it could be the holes (but I also had my filter packed full of media which reduced the flow, never had the bar end caps blow off..)
 

naughtymoose

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Hum,

Filter 306 #1 has a longer pipe run as it is on the left-hand side. I removed the extra noodles that I'd put in tray 2 and put them in with the similar amount in tray 2 of 306 #2.

I then was able to crank both up a bit. I also noticed that over time the whistling dropped substantially. Perhaps this may be the effect of trapped air working its way out of the system?

I'm going to have a go at adding a few extra holes too, but am a bit under the weather at the moment and will have to wait a bit!

Does anybody have any input as to whether it is worth having some outlet holes pointing DOWNWARDS too?

I've got a small filter that I am going to mount in the gap between the two spray bars (permanently available to move into an isolation tank). When I fit this I shall report back on changes.
 

Rahms

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generic answer for downwards holes in a spraybar is that its bad. You should be able to get good circulation without them, and adding water in a different direction makes it likely that it will counteract this circulation. Think of two cars travelling in the same direction vs opposite directions on the same road. Smashing them together doesn't improve your distribution!

On the other hand.... if you have tall dense plants that will block any circulation coming from the front of the tank, and they're showing CO2 deficiency, then yeah downwards holes could help. But I'd still rather trim... can't undrill holes!
 

naughtymoose

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Hi folks.

To stop the whistling I had to turn the power right down. After a while, I was able to turn it up to about 60% without the whistling.
Perhaps it was caused by trapped air in the pipes?

The biggest problem has been not being able to turn the power up to 100% for maximum circulation.

Today, I doubled the quantity of 3mm holes in the spray bars, and am now able to turn the filters on at 100% without disturbing the sand at the front of the tank. There is a very small amount of sand displacement, but it is minimal.
 
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I had this issue with JBL spraybar on an Eheim filter. The holes were way too small and the flow from the filter too strong and the spraybar whistled. I let it whistle for quite a while which resulted in the plastic cracking where the spraybar connects to the pipes. Eventually the impeller of my filter also cracked, not sure if related but the filter must have had quite the pressure on it.
Solution, I drilled the holes bigger and whistling was gone.
 

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