Loaches Online Forum

Hello everyone,
This is a really great forum, I've been catching up on some reading and I have a question for all fish keepers out there.

My tank setup is currently a 55 gallon with 5 loaches, 1 pictus catfish and 1 pleco running a Filstar XP3 and an Aquaclear 50 (formerly 402) powerhead (and for those wondering, the tank is planned to be upgraded to a ~180 gallon next year after I move, for the loaches' sake).

The tank is also lightly planted with fake wood logs and such for hiding places.

My question is - Are the bubbles necessary with the Aquaclear 50? I'm referring to the little plastic tube attachment they provide which will aspirate air from the room into the jet exhaust. Right now I have the powerhead next to the filter exhaust pointing in the same direction to create a respectable current that keeps the plants waving and the water moving. The surface of the water in the tank ripples in the same manner as a bed sheet if you were to wave it up and down with someone outside.

The reason I'm asking is because those bubbles make quite a noise and if the circulation and oxygen exchange is decent enough, I'd like to forgo their addition.

Thanks for all and any help.

hi ctabone
as you say the surface ripples with the current, so i see no need to put the ventura on,
if your fish look alright why change it.
if you want the surface agitated a bit more angle your power head towards the surface.

btw, what loaches are they, don't say it "clowns" haha
mick

They would be Chromobotia macracanthus good sir.

thought so, i seems to be the most popular.

i must remember to use latin names in future, haha

mick

I do not use the venturi on any of the powerheads. There is plenty of water movement without introducing the bubbles. I run most of my PH lower in the tank, too.

What exactly do the bubbles do, anyway?

I know a bubble wand at the bottom of the tank will create more water movement as the bubbles rise, but bubbles from a PH are already at the surface.

From what I've been reading it is thought that they may help with oxygen exchange by agitating the surface of the water.

There is a book I found online which hopefully is available at my university entitled, "Biogenic Trace Gases: Measuring Emissions from Soil and Water" by Pamela A. Matson and Robert C. Harriss which goes into great detail describing the models and theories behind gas exchange at the water's surface. If I can get a copy I'll post some info here. Google Books has a couple chapters online but unfortunately not the ones that deal with how bubbles effect gas transfer.

Diana wrote:What exactly do the bubbles do, anyway?

I personally find it very useful to indicate whether the flow is loosing strenght. When I don't see bubbles anymore I know it's time to clean it.

I keep the venturi feeder tube in mine, but with the valve closed down. I do this because I once found an over-curious Yoyo with his face sucked into the intake. He was alright once I got the thing turned off, but they do create quite a bit of suction.

mine is too deep and won't suck down surface air. Never had an O2 problem before with other flow and bubbler, but hooked the bubbler to the power-head today to see what happens. Will turn on tomorrow. I'm expecting some loss in flow rate and an upward slant in the flow with bubble rise, so may not use much. Will report. [/i]

Use of the venturi action will reduce actual water flow a fair bit depending on how much air you let in. If you run the powerhead(s) deep the venturi will not work and it will require a positive air-feed from a small air pump.
Since losing some Clowns to a filter blockage that reduced water movement and aeration, I now have a powerhead that uses the air venturi to provide constant aeration in event of another disaster like that.

Martin.

My question is directly related to Martin's post.

Venturi reduces the water flow. This would suggest there is less aeration because of reduced water movement, less chance for gas exchange.

Or does the venturi create molecule sized bits of air that does raise the O2 level more than the increased gas exchange (with higher water flow) at the surface will?

My major surface movement is by the action of a spraybar angled upwards a few degrees below the surface. This gives a lot of agitation to the surface. This filter got it's intake blocked by plant debris and the surface agitation stopped. I have a River-Tank manifold on this tank and one of those powerheads is aired up. For me, the use of the air is just extra insurance.

Tank has two Rena XP3's on it, an Aquaclear 500HOB, the R/T manifold with an Aquaclear 802 and 402 and there's a Seio 1500 GPH powerhead also. Oodles of water movement.

Martin.

hooked a splitter at the air pump so now have air bar/stone and trickle of air into powerhead. yes, too deep for venturi to work. Seems to be very nice, with no noticeable differences in powerhead or bubbler flow. Looks great in morning sunshine.
A

Currently in my office I have a 80 gallon tank the main filter is a fluvall fx5 plenty of water movement on the surface ! I also have a power head 420 and a Aqua clear 70 with the filter attachments. I did a revamp on the tank creating 2 tunnels systems for my happy bunch and used bog wood to create a couple of calm area's.

What i noticed was that my large clowns would play in the current of the 420 which had the venturi attached and so just to experiment I attached the venturi to the 70, and positioned it towards the front of the glass then I repositioned the 420 to push the jet of the 70 against one end of the tank.

As one end of the plastic tunnel is under the stream it recieves a circuler whirpool stream of water my big guys swim to the end and then swim up into the current flipping over on their backs riding the air bubbles then when they have had enough they just glide back wards to the calm end of the tank or the back of the tank as the flow of water travels down the front glass of the tank.

Since I have done this I see more of my clowns every day .
I just thought I would share these observations.

Thanks for all the replies everyone.

Diana - that's exactly the question of balance I've been pondering for quite some time now. Most people seem to agree with Martin's spraybar statement that the surface agitation is caused more by the direct movement of water in comparison to the bubbles (in other words if you had a choice between the two, pointing a jet of water towards the surface is much more effective). It seems that just creating the flow around the tank where the surface water is constantly displaced is sufficient to distribute oxygen throughout the aquarium. I may try the powerhead with the air off and decide based on the loaches' behavior.