I'm starting up my 40g breeder. What should I use for flow? I have the following available:

MaxiJet 400 (100 gph impeller)
MaxiJet 1200 (300 gph impeller)
Koralia 2 (850 gph propeller)
MaxiJet w/ small mod (1600 gph propeller)
MaxiJet w/ big mod (2000 gph propeller)

Which one should I use?

Also, I have some lily tubes for my XP1, will my Cardinals get sucked up the 3/4" intake? There is no mesh cover on it or anything...

It all depends on how much water movement you want or need. I have used a maxijet 600 in my 20H, and it seems to move lots of water. The xp1 is probably a bit small for a 40 gallon, depending on how heavily planted th tank will be. Some more info about your planned setup may help a bit...

Is the lily pipe just open ended? If there is no strainer on the intake of it, fish could potentially get sucked in, but they may be OK. You could maybe fashion a strainer or try to buy a clear one to cover the intake

The XP1 gives me a little over 6x turnover...isn't that enough? The lily tube is just open-ended and round. I'll see if I can locate a clear mesh intake. Maybe an AquaClear intake or something...

You must be coming over from the reef side of things.

I've never seen anyone put much emphasis on water movement in a planted tank. The general assumption seems to be that any surface disturbance will increase gas exchange and lower the available CO2 in your tank. I suppose there could be some benefit to a very low mounted, low volume powerhead in keeping detritus from settling on the bottom, but on the other hand I've always though of that as free fertilizer.

Another thing to consider is how your plant species will respond to water flow. Whenever my water level drops below a certain level, the output from the filter becomes more turbulent and causes the plants to bow over, ruining my aquascape. I've found the plants look best when the water is as still as possible, and they grow straighter as well.

Well, it's important to remember that the flow ratings for the filters isn't really applicable to planted tanks. The plants will obviously change the ability of water to flow throughout the tank. Good flow in a planted tank is actually pretty important, as dead spots in the tank can lead to trouble (ie. algae). Plants need to be able to access nutrients, and without proper water flow, this can be a problem. Just my $0.02, though. Good luck with the new setup!

The Hydor Koralia might be a good choice for a planted tank because it has a diffused flow rather than a powerful direct jet. I think that would work well for moving water around the tank without blowing over your taller plants. They're also cheap and small, always a plus with any in-tank equipment.

You're thinking about the advertised flow rate without media that's rated at 250 US gph.

This info comes from the boxes that the XP's come in:
Water flow with Filtration Media and Accessories:
XP1 - 142 US gph
XP2 - 160 US gph
XP3 - 187 US gph

Several folks emphasize higher current, myself and Tom Barr included.

A lot of it is just overcoming a huge mass of plants. If you have a jungle tank like my 75g then... well I have in it up to 2 Koralia 4's (1200gph ea) a MJ1200, and 2 XP3's. I still had dead spots.

The only reason I would avoid excess surface current is perhaps with DIY CO2. With pressurized the CO2 is cheap and folks who keep their surfaces still are taking a big chance to save a couple bucks of gas. CO2 is cheap. Current is good.

I love the propeller type pumps. However one of my Koralias is making terrible noise after about a year (will have to check the actual date and warranty info). The smaller ones have ceramic shafts I think, perhaps they might be better long term, not sure.

For the maxi jet prop mods are you talking about the Sure-Flow kit? The only think I worry about it is if you have small fish, it has a good amount of pull in a smaller area than the Koralias as well as much larger holes. Something like a neon might be able to get sucked in easy. And the front is pretty open, a loach could easily get into it if you have fish like that. I'm working on some mods for the Sure Flow to make it small fish and loach friendly, as I plan on having a couple in my 240g.

MJ1200 with SureFlow mod.

Thanks for all the opinions guys!! I actually didn't expect there to be such dramatically varying opinions! I am coming over from the reef side of things where I have 30x turnover just in powerheads. Thanks for posting that info Left C - I had NO idea the media changed the flow THAT much! Wow! Maybe the XP1 won't cut it... I'll try it out though since I bought it for $40 including the lily tubes. I am talking about the Sure-Flow mid kits for the MaxiJets...good point about the big holes. Never thought of that. I do plan to have A LOT of Cardinals, but nothing smaller than that.

Cheers!

Cardinal tetras prefer slower water movement- just something to keep in mind.



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You're welcome.

I wish the rates with media were advertised. All you ever see in the XP adds is the flow rate w/o media, but they don't tell you that is what they are advertising.

It's a little odd to me that the flow rates with media isn't included on their website's XP's specs. It's only printed on the box. http://www.marsfishcare.co.uk/en_us/filstarspecs.asp

Anywho, here's the manual for it if you need it: http://www.marsfishcare.co.uk/en_us/...aFilStarXP.pdf

Yeah, they boast the big flow numbers when in reality you wont ever get that. On the box, in small font, is the truth

But it doesnt really matter IMO. Yeah for flow they are underrated, as most are, except maybe Eheim. But as long as their is enough room for the media you want, mechanical, bio, etc. then just supplement flow with a powerhead/pump. If you look at a lot of marine tanks they have lots of flow, but not through the filtration. They will have the Tunze, Sure Flow, Koralia, etc. or a closed loop system with something like a 3600gph Dart pump. The actual filtration (sump) is much less. However the XP1 doesnt hold much media either... so you might be pushing the limits there. Personally, I'd start looking for an XP3

Thanks again Left C for the links!! Maybe I'll just ditch the XP1, and use a bigger one. I never thought of biological filtration...in reef tanks you don't use media for biological filtration at all...that would be a nitrate factory and is no good in reefs!! The XP1 that I bought has the one chamber half full of ceramic hex things, and I was going to use bulk filter "floss" sheets to fill it up the rest of the way. Not good enough?

You're very welcome for the links.

I bought a XP2 for a 20 long that I'm working on and crazy loaches says to look for an XP3.

You can always throttle them back some, but you can't add nitrous oxide to boost their output.