Lily pipe vs rain/spray bar

[PeterGwee]

Vinz, what type of placement or outlets are actually fine as long as water is well circulated in the tank. You can measure your pH at various points of the tank (apply to mostly big tanks since small tanks don't need much circulation) while injecting CO2 to see if you have areas that are lagging and try to adjust the flow to get to those areas. Spraybars can be located at the bottom-back of the tank pointed forward along the gravel with massive currents with no problems of plants moving around that much.

Regards
Peter Gwee

[vinz]

Peter,

I doubt so in this case. The currents from the spraybars are very strong. Plants that are on the opposite end of my 6ft tank were swaying quite strongly with just one of the filter/pump running. Whether its along the top of the tank or the bottom of the tank, it'll be the same... given the same length of spraybar.

There is a distinct difference in the nature of the output... a non-tank analogy is when you compare water running out of a hose without interference and water spraying long distances with force when you restrict the opening.

This can alleviated with longer spraybars with more holes.

[PeterGwee]

The spraybars are side-mounted rather than the along the entire length of the tank? Well, if it works for you, it's fine as long as the tank is well circulated.

Regards
Peter Gwee

[vinz]

Exactly.... good circulation.

[celticfish]

hi all,

as mentioned in previous posts i have a lot of hi-tech equipment from an old-bird forummer that i haven't put to good use. but have all the time to check them out! was just looking at the ehiem 2028 spray bar and the lily pipe like outflow attachment (the ehiem green type) that i have.

here's another fluid dynamics point (i'm starting to see the value of the course in this hobby!). mass flow rate at any cross section must be equal at all cross sections of a pipe. as an example cross section area A has flow rate 10cm/s. then downstream cross section B has twice area A then flow rate becomes 5cm/s.

i have just measured the spray bar diameter 4mm with 9 holes. the pipe diameter is 14mm. so flow rate for pipe must equal the 9 holes along the spray bar. area is Πr^2 giving pipe 49mm^2 and spray holes 36mm^2 (multipled by 9 holes). this give a flow rate of 136% for the 9-hole spray bar vs pipe cross section. also with the differing pressure along the pipe the velocity of the water will get weaker towards end of the spray bar. so that the spray hole nearest the inlet will have the fastest flow and the end one will have the slowest flow.

now if you increased the area of the pipe like the lily pipe outflow... from the ADA pictures it looks like 4 times the size of the pipe. this will give you 25% flow rate of the pipe.

so if you take vinz's suggestion and double the spray bar holes (two spray pipes) you will have 68% of the pipe velocity. the green attachment i have is only double the size of the cross section although the opening looks like more than four times the top portion is not covered (please see benny's pic). i suspect the direction of the flow will not be as well controlled as the ADA ones (please see the link on this thread for the ADA pic).

celticfish

Peter,

I doubt so in this case. The currents from the spraybars are very strong. Plants that are on the opposite end of my 6ft tank were swaying quite strongly with just one of the filter/pump running. Whether its along the top of the tank or the bottom of the tank, it'll be the same... given the same length of spraybar.

There is a distinct difference in the nature of the output... a non-tank analogy is when you compare water running out of a hose without interference and water spraying long distances with force when you restrict the opening.

This can alleviated with longer spraybars with more holes.

[copycat]

Just wondering, how does a lily pipe compare to a spray bar?

For one, spraybar should limit the flowrate of the filter somewhat as the outlet is reduced to a dozen or so holes about 2mm in diameter.Or maybe not, as total area of the dozen or so holes added up will probably be about the same area as the normal outlet.

But it does generate jets of water.

Given the same flowrate, will the lily pipe provide a more gentle solution?

Woh, there seems to have a whole lot of engineering ppl in this forum.
Anyway for me, i would prefer lily pipe, less maintaince issuse. I had tried out the spray bar once, and after something, alage start growing inside them, had trouble removing them. Looking at the design of the lily bar, it does look to smoothen out the flow as compare to spray bar. Yes, I assume spray bar would reduced the flow of water slightly, as you created more resistance for the outlet water flow, that why you have all the spray coming in. As resistance increase, volumetric flowrate should decrease rt?

[cbong]

Its interesting to learn that spray bars can be placed at the back bottom of the tank. I thot its normally at the top.

Anyone has a picture to show how you set it up?

[PeterGwee]

Its interesting to learn that spray bars can be placed at the back bottom of the tank. I thot its normally at the top.

Anyone has a picture to show how you set it up?

Just make sure you have some surface movement to go along with it just in case plant production goes south.

Regards
Peter Gwee