been fiddling with durso for a week now and it will only run at acceptable noise levels when the outlet is restricted. (i have a ball valve immediately below tank fitting under tank) seem to be combating 3 types of noise

1. waterfall noise as water launches thru comb into overflow box (many thanks to the person that sold me a laguna 7 )

2. water rushing down the 40mm drainpipe

3. air sucking noise at the durso cap (much like the doris used to make in the early days when i asked her if she minded if i went windsurfing. 8) tip; just tell her your going ,never ask permission

anyone got any helpful comments??

got a pic? i assume the durso pipe itself is bigger than the outlet from the tank? mines 40mm durso, 32mm outlet, 40mm drain pipe

Durso's are noisy, there's no way around it. It's a flawed design in my opinion, and doesn't solve the problem it was intended to.

What they did was take what was once uncontrolled air entry into the overflow, and change it so it was more controlled. Sure it reduces the noise, but it doesn't eliminate it.

If you want to eliminate the noise, you have to eliminate the entry of air into the overflow completely.

I think Cracker has it worked out (at least from what I gathered from his posts here), so if you can take a look at his setup, you might get a better idea of how to do it.

Layton

i prob cant load 1 tonight, at the mo would show water level within 5mm of tank and total submersion of durso except for top which has no cap. seems that the drain has such a high capacity that shutting some down is the answer.

i had a good look at crackers and would consider that type on any new tank, extra holes needed etc. basically he was restricting outflow but using 2 x different size valves, totally submerged, to tune the rate.

drill a bigger hole, sounds like water level is too high - i assume its surging?

Ok then maybe crackers is not setup how I thought. I'll tell you the principle behind how mine works.

You just stick a plain pipe in the overflow box, no elbows or anything, just sticking straight up. You have it so that the top is about 200mm or so below the level of the overflow comb.

You then tune the tap at the bottom of the overflow outlet, so that the water level in the overflow box is around 100mm above the top of the stand-pipe.

It has to be high enough that now air is sucked into the stand-pipe.

So now you have a dynamically adjusting silent overflow, as no air is entering the overflow tube.

It's self adjusting in that if for whatever reason the return pump starts pumping more water, the water level rises slightly in the overflow box, and the effective head of the overflow system increases, and you get a higher flow rate out, and vice versa. (To a limit obviously)

Layton

tried all sizes of holes and now no cap at all. i did have surging early on but adjusted the pipe entry height into sump to fix that. basically ive found best results running similar to laytons design, except i cant run a 100mm drop from tank water to overflow water levels or it sounds like a waterfall due to the laguna 7. hence no head height spare capacity inside box as only about 15mm difference works, which looks pretty risky. i may have to mechanically deal to ''waterfall'' to achieve any spare capacity.

turned lights on to do above and the water is real green and lots of floaties so massive water change due asap :-?

You do have a skimmer running don't you?

yes deltec1250t running a little on the dry side. pulling a fair bit out every 2 days.....

some of this new rock was pretty smelly to begin with.. :-?

got a pic? i assume the durso pipe itself is bigger than the outlet from the tank? mines 40mm durso, 32mm outlet, 40mm drain pipe

yup, rule 1 on the durso site. tank fitting 32mm and durso and all drain piping 40mm same as yours

Don't know anything about Durso's, however as to the water barreling through the overflow comb & making noise, I had the same thing & was able to solve it by getting several strips of glass an inch or so wide, and siliconed 2 on top of each other immediately below the comb, enough to catch the water. Below them I siliconed a single strip angled at the bottom towards the glass, then below that a thin strip, and all this pulled the water in & back to the glass, so took 90% of that noise anyway.

Just FYI, I saw a Durso running on an FW tank, not sure about flow rates but it was silent.

mines silent

quiet and silent are two different things

mine is quiet, and certainly one hell of alot better than it was before. noise level also, to a certain degree, depends on return pump/flow back from sump (thus flow out of main tank)

I had similar problems when I first setup my durso, I tried playing round with restricting the flow by turning down the tap, etc but had problems with the tank level creeping up. I had pretty much given up, then I added a 45 and some extra length of pipe to the return which added a little resistants and it all started working.

I agree that it is almost impossible to have a silent durso, however they can be very quite if setup correctly, and the point of the durso is to make it quite AND safe. There are very few non-durso setups I have seen that I could comfitably sleep at night with (the only one that comes to mind is SteveA's setup) I don't believe using taps to contol the flow is a safe long term option even with added redundancy of extra over flow. But thats just my opinion. I also wont use push on fittings, or power without an RCD in line, where as some people are happy to do so.