Why point powerheads towards surface?

[Rakie]

I've seen a few people recommend pointing their powerheads towards the surface. And I've yet to see an explanation why -- Obviously it's beneficial or it wouldn't be done.

So does it generate a gyre effect, or does it just help randomize flow?

 

[tdileo]

Surface agitation for increased gas exchange, some people like the shimmer it gives lights, and I’m sure there’s another reason somewhere :)

 

[EriksOasis]

It provides surface agitation and helps keep particulate matter suspended for a longer period of time to be removed my skimmer or mechanical filtration. Also helps with just creating random water flow which is beneficial to coral and fish.

 

[saltyfilmfolks]

It adds to gas exchange.
Depending on where the head is placed and type of head it can actually add to the mass water flow.
I.e. A Koralia has a fairly narrow flow. Lower it , point it up, and after it hits the surface it spreads out.

Good trick for cheap pumps.

 

[Dan I]

It provides more oxygen exchange. In addition, different type of flow pattern as well.

 

[TangingOut]

Surface agitation for shimmer, added flow, randomized flow, gas exchange, prevents surface film. Those are pretty much my reasons in no particular order.

 

[brandon429]

no googling

what aspect of aiming it towards the surface makes the water table take in more o2 than a stilled surface, but its running all circular underneath

if anyone recalls the amazing site aquaticeco.com that place was the baddest mariculture and aquaculture place in the world for sure, miss it

they used to give little scientific tutorials in their mag, and in that was amazing knowledge about the difference between aeration w bubbles vs pumps I never knew the dynamics were so skewed towards air working better due to X variable above

that means even a basic airstone will aerate the water better than probably quite a large underwater pump, per their stated physics.

 

[tdileo]

no googling

what aspect of aiming it towards the surface makes the water table take in more o2 than a stilled surface, but its running all circular underneath

if anyone recalls the amazing site aquaticeco.com that place was the baddest mariculture and aquaculture place in the world for sure, miss it

they used to give little scientific tutorials in their mag, and in that was amazing knowledge about the difference between aeration w bubbles vs pumps I never knew the dynamics were so skewed towards air working better due to X variable above

that means even a basic airstone will aerate the water better than probably quite a large underwater pump, per their stated physics.

If I recall correctly we don’t like air stones in saltwater because of the way the bubbles will stay present in the water, kind of like how a protein skimmer works. In FW tanks the bubbles pop but in saltwater they stay around for a while and are unpleasant to look at and can irritate corals.

 

[Greaps]

I think people aim up to increase turn over without directly blasting corals or their sand.

 

[norfolkgarden]

Gas exchange would be the number 1 reason to point the pump upwards. The other reasons are noce but nowhere near as important.

A still surface is a stagnant surface.

Not recommending turning your pump into a fountain, even though that would give you an extraordinary amount of gas exchange. But moving the surface water gives you the ability to add more oxygen to the tank.

It's the opposite of why your fish die when you lose power for an extended period of time.

 

[Somuchflo99]

I also heard air bubblers can lower the ph

 

[Somuchflo99]

Is that true

 

[brandon429]

They'll lower it if they're pulling in high co2 air from the surroundings (learned in Randy’s Chem fm) and they’ll raise pH if the ambient air has less co2 than the tank

That answer is waste gas dependent




We run our pico reefs solely on air so it's ok for corals, but we use special lid fits that prevent salt creep from happening. Normal tanks get lots of creep so airstones are less common in display agreed

Aquatic eco detailed surface boil and I never forgot it:

Stilled water is flat and has X surface area where gas exchange is always taking place even if we move nothing

Moderated by variables such as fats/oils and various ambient conditions, the only way to increase o2 and co2 out given all other conditions was to create surface boil, the ripple effects on the water whether by powerhead or airstone. Now the flat plane is a series of little mountains, massive surface area increase for the gas exchange already set by partial pressures and various water conditions


So it’s not that we are increasing rate of exchange, as much as we are increasing surface area for an exchange already in place


The surface boil from an air stone typically beats that of a powerhead, though they have negatives that curtailed their use in displays in modern times in aquariums. in lake management and river management, they use air not water pumps

Perhaps a powerhead one inch under the surface shooting up a three foot fountain would win, but in practical tank settings given controls of the negative characters, an air stone will beat even an oversized powerhead for oxygenation. In emergencies this is helpful

On a battery setup the cheap bait box bubblers will run days or weeks, a powerhead only a fraction and the tiny bubbler will be the most egress and ingress one could get.

The aquatic eco education points always included the aspect of laminar flow vs random flow when dealing with oxygenation in systems management: laminar flow straight up and down cyclic is the pattern of the air stone, a round current pattern which is the most refreshment you can get for surface-mediated exchange

Anything other removes efficiency, like when a filter system has its inlet too close to the outlet and double filtration occurs, laminar flow directly promulgates air exchange more than random flow + inherent surface boil= air stone unbeatable but only for exchange...which may or may not be needed. In lakes experiencing fish kills merely making a thirty foot tall column of bubbles can stop the kill and change the limnology of the entire lake within five months. That site was sick, it’s a sad loss. They were eco system masters agreed

 

[Somuchflo99]

Ok so how about a air stone in back of all in one tank

 

[Somuchflo99]

I get no movement in back of thank films up like crazy and it wouldn’t be in the main display just to keep things moving in the back

 

[brandon429]

the problem is square-fitting lids which is most large tanker's design

no lid at all means the popping bubbles w splatter around even if its on low, and a lid that rests on the top lip of the tank makes saltcreep around the edges.

the only way pico reefs get away with it is that our lids fit the inner diameter of the tank, pressing outwards, not resting on top pressing downwards.

this directs all splash right back down and none of it gets out as saltcreep even if our air is way overpowered which mine is (air pump for a 100 gallon tank runs 1 gallon pico)

you may certainly use an airstone for movement at any time, but dealing w saltcreep w be tricky in a normal setup. if your pH hasn't been a problem so far due to Co2, then the airstone cannot hurt your setup though many would choose the powerhead at the surface for that reason, we don't need extra o2 in our reefs we got plenty

whether the whole action is even needed in a reef tank is debatable, I have never seen a reef post I thought reflected poor oxygenation. I know the surface slick is annoying, that's a common method to break it up. I never worry about them past looks though, imo mixing them into the water vs collecting on top is just out of sight/out of mind they're not stopping our gas conversion considering motion in the rest of the tank. an airstone set on a bleed valve so you can control power might be ok, but that saltcreep is really hard to contain for sure.

 

[Rakie]

Awesome information guys! A lot more than what I was assuming.

My gut was telling me gas exchange and different flow patterns -- But Here we have a lot of people giving other reasons which were much less obvious (at least to me)

 

[alex.mccann99]

I would also add another reason is because many corals don't like "direct" flow pointing at it, but rather more random flow spread out. If I had my return pump outlet pointed down it would blow the sand all out of the corner it's pointing towards. With it aimed slightly upwards it spreads across the top and creates even more flow in the entire tank. Hope that makes sense...

 

[s2nhle]

Great information. Learn something new.

 

[TheRealDmorty217]

If higher O2 levels are what you're after, lower the temperature is a easy fix and more beneficial than a powerhead pointed at the surface