Flow - enough is never enough

wayne

Elite Fish
Oct 22, 2002
4,077
3
0
#1
Often people underestimate how much flow is required in a marine tank, or rather they never get to see the benfits of adequate flow as they are scared of overdoing it.

Don't get me wrong, there are some fish out there (seahorses for example) and sessile organisms and plants that do better without seemingly brutal amounts of flow. For things such as lps you can cut the flow, or place them in sheltered locations in your hopefully admirally aquascaped tank ( that does not look like a fruit stall) with plenty of features to create sheltered areas.

However for many organisms a whole load of water movement is not going to hurt, and for some things it is a positive advantage. For instance if your interestes extend to tangs, anthias, fairy wrasses, chromis and plenty of other fish, and the obvious suspects for sessiles (SPS< zoanthids, colonial polyps, clams and so on) these organisms are used to, and can deal with flow that when diving will be a positive menace. I have seen some pretty stern currents when diving, but have never felt the current in my aquarium is likely to kill me! Most organisms are caught from shallowish water in what are considered medium flow (6 - 20 cms per second) enviroments. If you've seen a high flow enviroment you will realise it is not practical to hope to reproduce this in the home aquarium ( up to 1 metre per second velocity)

Right now in my tank I'm up to approx. 50 times per hour turnover. This seems a lot, but my stock of pretty ordinary fish seems to handle it pretty well. Some fish still swim in open water, my wrasse, angels and clowns still stick close to structure.

What I'm saying is be sensible, you don't want a washing machine effect, but don't be scared of having your fish or inverts swept away and destroyed.

What that means is that rather than having one great big parallel flow organise your flow so it becomes turbulent and changing, rolling. Point powerheads to cross flow. Use 'propellor' style pumps rather than traditional powerheads if you can get/afford them. Split and direct the flow from your return pump, again to cross, interfere and bounce against other flow sources. With these new, high flow pumps (that are at the same time gentler, but carry further) it is now possible to really get to grips with wave maker machines - mine varys the flow from my main pump between 2500 and 5000 litres per hour on a 20 second basis. Previously some people considered wavemakers a p.i.t.a. as they were very limiting on pump efficiency - this is no longer the case. My flow is deliberately bounced off and around a rock pillar to improve turbulence.


The benefits of high flow are many. Better oxygenation. Better supply of food to sessile inverts. Excercise for your lazy fish. For me the favourite is that I believe it helpes with your filtration. By not allowing debris to settle it is more available for removal by mechanical means (inc. a skimmer), and less available as an algae fuel - one of the killer problems with hair algae is it traps debris - not any more. Also increased flow across your now debris fre LR will allow 'normal' fltration involving the nitrogen cycle to proceed better.
 

Last edited:
Likes: JWright
Jan 16, 2004
1,669
6
38
32
Syracuse, NY
#3
Very good read

Now this might be too off topic but I have a question regarding "fruit stall" displays. Does anyone happen to have a picture of an example of this? I understand its when corals, rock, etc are just piled in random places and theres no real order but can I get some examples? (feel the definition is a bit un-informative) Id appriciate it.
 

Jul 29, 2005
443
0
16
43
Sunny Cali & Rainy England
#4
I read the fruit stall effect as meaning a pyramid style of aquascaping (like a pile of apples) devoid of caves and interest and such like.

I have all (3) of my powerheads gathered in the same corner of the tank, around the HOB inlet to the sump for aesthetic reasons (afterall, thats why I have a sump) and all pointing in the same direction. Pointing them in different directions meant that a film accumulated on the surface of the water because all flow was away from the skimming sump inlet. The only way I found to overcome this without spreading the powerheads around the tank was to point them in the same direction and cause a circular current.
Good to know that many fish can handle stronger currents.
 

Last edited:

wayne

Elite Fish
Oct 22, 2002
4,077
3
0
#7
Frankly many tanks are 'fruit stalls'. Rocking cricket has got the idea, but many of them just like a pile or a wall of equally shaped roundish boulders needly stacked together just so, and then to really cap it off a nice selection of small frags spattered across the rockwall, one every 3 inches. This has no shape, no featuring to disrupt flow and create turbulence. Many so called 'tank of the nonths' unfortunately suffer from this, but creme de la creme tanks usually avoid it.

If you had a HOB overflow I can't see how you can have a film accumulating on the surface unless your overflow is a little too deep in the water and it never gets pulled down.
 

Jul 29, 2005
443
0
16
43
Sunny Cali & Rainy England
#8
wayne said:
If you had a HOB overflow I can't see how you can have a film accumulating on the surface unless your overflow is a little too deep in the water and it never gets pulled down.
Well, it accumulates because the power heads are mounted on and blowing away from the overflow inlet. Therefore the water at my tanks surface is always being pushed away from the overflow inlet and with that any floating particles are pushed to the other end of the tank and held there. As I said the only way I can release them, and keep the powerheads where they are, is to cause a circular (washing machine) current.
 

Jul 29, 2005
443
0
16
43
Sunny Cali & Rainy England
#10
Not a cabling issue, just an aesthetic one because I have my tank dividing my lounge and dining room, with the tanks side against the wall so that it can be veiwed from the front or from the back (if that makes sense). It's sticking out from the wll instead of being flat agaisnt it as is traditional. Therefor if the powerheads are anywhere but near the side of the tank near the wall, they are very noticable.
The current powerhead placement seems to be working okay. If there is a washing machine effect, it doesn't appear to be bothering anyone and there don't appear to be any dead spots. I don't want to clog up this sticky any further, but can I confirm how do you identify dead current spots? I am assuming they are highlighted by an area where uneaten food and junk accumulate?
 

wayne

Elite Fish
Oct 22, 2002
4,077
3
0
#11
You'd be better off running a closed loop along the top where you hide it with the hood for the most part, and running a big powerhead deep and low (though hopefully not throwing up all your substrate).
Food, junk and cyano usually mark dead spots
 

Feb 28, 2005
569
0
0
34
Waterford, CA
#12
Wayne, or any one els that could reply, first I have a question about inverts. Would to much water flow restrict your "clean up crew" from getting enough food? Because they are scavingers, dont they need food to settle on the bottem of your tank? I mean, I have a lot of water flow in my 60 gallon(like at leaste 900gph(with skimmer)). but when I feed my hermits they go crazy and start running around and all. And I shut off to of my maxi juts(sumtimes) and the hermits all come out and look for food or whatever. When I have all my power heads on they dont realy wonder around. Ok I think thats it sorry so long, lol. what do you guys think?
 

wayne

Elite Fish
Oct 22, 2002
4,077
3
0
#14
Your feather dusters can easily absorb 900 GPH from maxijects. If you put your hand in front of a maxijet at 1 inch distance and move it away feel how quickly the flow drops away. At 6 inches it is just not powerful (another plus for the seio/tunze stylee). And any, depending on how you do it , 900 GPH in a 60 , esp if you inc the skimmer is a pretty low flow enviroment - low, but possibly adequate.
Anyway, if your clean crew aren't getting enough food that is good, get less clean up crew
 

FroggyFox

Forum Manager
Moderator
May 16, 2003
8,589
10
38
39
Colorado
#15
Hey all...for informational purposes could we list some product reccomendations as far as pumps go? I read Seio and Tunze as brands who have 'propeller type' pumps, but I know those two are both a little more spendy than other types...and I dont know what type of models they have that might be better than others.
 

Jan 16, 2004
1,669
6
38
32
Syracuse, NY
#18
Heres a quick sum-up of several commonly avaliable powerheads

Tunzes'- really good, solid broad flow, can hook up to wavemakers, etc, popular in europe, many swear to them, can be found online

SEIO's- good, solid powerheads, produce a large, broader flow "poor-man's tunze", still not really that cheap though.

Hydor Koralias- good at being contorted to face different directions, decent broad flow

AquaClears, penguins, maxijets, etc produce a thin stream of flow that tends to lose alot of current as distance increases, not too expensive
 

TRe

Elite Fish
Feb 20, 2005
3,645
1
0
ft. lauderdale
#19
i couldnt imagine the flow being any broader than my koralia ... in my 125g i have it about in the middle of the glass on the side wall and not only does it break the surface but the flow also hits the bottom and both sides and thats just with one #3
 

TheFool

Large Fish
Apr 19, 2006
323
2
0
#20
The differences in flow 'style' between the different propellor pumps are pretty minimal - the differences are in quality, features. Pricewise, from the top, I tihnk

Vortech - go look there are huge pros, also a couple of big cons. You're going to love them or hate them. I think they have a speed controller out now.
Tunze turbelle streams - the original designers. Big range, with some big volume ratings. Super reliability, single and multi controllers for speed controller (6000 + single controller is big bang for the buck), light sensors to slow them down at night.
Seio - some quality problems, have they got that controller out yet (I think answer is yes in theory, but I've never seen one)
Hydor Korallia - cheap, flow is good, noise not so great, some reliability issues, they've been recalled once.

Also throw in that mix the nano streams fomr Tunze that are great value for money, but initially had some QC problems. If I was looking for pumps for tanks up to a 55 or 4x2x2 120 that's what I would get, and mod them to up the flow (see reefcentral). There are also similar pumps fomr AquaMedic, and others, but I've not seen them

And then, in Europe, the situation is confused even more by the fact that on a rating for euro per litre moved the difference between seio and tunze is very , very little (10 ~ 10% dearer) if you shop around, and if you include speed controllers seio is actually a little more expensive according to some calcs.

FWIW I use original tunzes, with one of them on a single controller. Mins brush streams to create a turbulent vortex, and with the single controller set to vary between 30% and 100% every 15 secs I can get the vortex to move up and down the lengh of my tank.