Flow: How much is enough? What's a deficiency look like?

[Oreo]

How much flow is enough? I'm not looking for a tank turn-over rate, but more of an inch per second type of measurement. If I look at a piece of debris suspended in the water I can see what the water current is doing in that area by watching how the debris moves. I notice that nothing is ever stagnant anywhere in the aquarium. The fish are constantly stirring up stuff. So how much is enough?

I contemplate this and then I realize that densely planted areas might need more focused flow to move some water through but then I think about how dense the pots of dwarf hair grass are and realize that getting much circulation at all down in the thick parts of a DHG bunch will be nearly impossible even with thirty foot waves crashing around in my aquarium. I'm not sure how that adds to the question but it makes me wonder how much is enough?

I'm contemplating buying a drastically larger pump and going for 20x / hr turn-over. "low pressure" flow of course, but still...

Your thoughts?

 

[dutchy]

Hi,

You could have a look here:

http://www.barrreport.com/showthrea...ment-and-ther-sediment-from-Madsen-et-al-2001
http://www.barrreport.com/showthrea...ons-for-planted-aquarist?highlight=wavemakers
and here:

http://www.jlakes.org/web/Interaction-watermovement-sediment-macrophyte-H2001.pdf

If you're in the 2 inch per second range, you're doing fine. I keep in mind that all leaves have to move gently but not to bend plants, which induces biomechanical stress and decrease in biomass. That means that I have a flow of maybe 10 inch per second at water surface level where there are no plants, but gives me a nice ripple at the same time.

regards,
dutchy

 

[shoggoth43]

I just aim for the all plants moving somewhat range. Dutchy's 10" or so at the water surface puts him around 1/2 mile per hour in speed which is a pretty lazy flowing stream. There's little reason to go much beyond this unless you're into the salt water stuff or you have some specific species of fish that you want to give a more natural habitat to. I would think that the 10x+ turnovers per hour in the tank would be adequate.

If you want a better ball park with some numbers, figure out how many gallons you have per inch of tank. i.e. 90 gallon tank at 48" feet in length will give you just under 2 gallons per inch. Pick a figure like Dutchy's 10"/second and you have 20 gallons per second X 60 seconds => 120 Gallons per Minute x 60 minutes => 7200 Gallons per hour / 90 gallons ( tank size ) => 80 turnovers. Drop that number down to 2 inches per second and you have a more reasonable 16 turnovers per hour. The amount of current in this ballpark estimate is on overall average value. You aren't going to have the same amount of current flowing in the tank all in the same direction at the same time, but you can at least get an idea that your 20x prop pump ( or whatever ) will get you something like 2.5" / second average. Much less in some areas and a LOT more in the main plume out of the pump. Depending on your needs, a smaller needle wheel powerhead for CO2 and a smaller prop pump may give you better coverage for less money / electrical use.

-
S

 

[Oreo]

I've decided to double my mechanical filtration flow capacity and triple my pump flow capacity. Here's to hoping my aquarium doesn't just turn into a geyser.

 

[dutchy]

I also think it's better to use multiple smaller pumps than one big pump. Better coverage and less unidirectional flow is better. Plants move, but do not bend that way. I let them work against each other. That creates a downward flow in the middle of the tank, like some kind of vortex. I can even see the CO2 bubbles hit the substrate, and pass the tank everywhere before they can reach the surface. Then I use the Eheim filters and MP40 to pulse the flow, so the path is constantly changing.

That way I don't use very strong pumps and my total is 2000 gph on a 180 gallon tank, 11 times turnover.

regards,
dutchy

 

[shoggoth43]

Hose clamps help cut down on the geysers. Also, as noted elsewhere in another thread if geysers are a concern, GFCI outlets are not a nice option. They are ABSOLUTELY REQUIRED for aquarium usage. When a hose lets go because you nudged something you won't have time to hit a switch or anything before you're in a puddle with a soaked power strip at your feet or the "entertaining" results from a flourescent fixture falling into the tank. Not that I speak from experience or anything like that....

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S

I've decided to double my mechanical filtration flow capacity and triple my pump flow capacity. Here's to hoping my aquarium doesn't just turn into a geyser.

 

[dutchy]

Hose clamps help cut down on the geysers. Also, as noted elsewhere in another thread if geysers are a concern, GFCI outlets are not a nice option. They are ABSOLUTELY REQUIRED for aquarium usage. When a hose lets go because you nudged something you won't have time to hit a switch or anything before you're in a puddle with a soaked power strip at your feet or the "entertaining" results from a flourescent fixture falling into the tank. Not that I speak from experience or anything like that....

-
S

You could have fooled me....

regards,
dutchy

 

[Oreo]

Considering I'm plumbed 100% with rigid PVC, hose clamps aren't going to be an option.

GFCI outlets... well, yea, then there is that.

 

[Gerryd]

Oreo,

If you can use the flex PVC I advise it....union fittings are all very useful with PVC....the flex is easier to use, quieter, allows some movement, etc.

I have a heavy duty GFCI that is used for outdoor swimming pool/spa applications. I plug that into the wall and I have a 6' strip outlet plugged into the GFCI. I plug everything into the strip so it is all controlled by the GFCI.

One of my better investments. Water and electricity do not mix well for us....

I think all of us should use one if we can...

 

[Oreo]

Well I fibbed a little. I do have some flexible PVC in a few places where it makes sense.

As for the GFIC... I prefer to use the GFIC circuit breakers in most cases. One breaker covers every outlet on it's circuit.

 

[shoggoth43]

Just make sure to test the GFCI every so often. They do eventually fail. Friends who have reef tanks and floods and poorly placed outlets with regards to stands = much amusement, until you are tasked with "helping" which generally translates to doing the whole thing for them....

For the record, reef tank = sharp/pointy/venomous/territorial/vindictive pests hiding in rocks. Fortunately for them, trying to zap them with electricity doesn't work so well, unfortunately for us, salt water and alternate path to ground i.e. you or me, zapping with electricity is very effective. The ideas you can come up with after getting bitten by something only to jerk your hand away onto a fire worm border on epic....

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S