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Advice Needed

Robert F Porter

Thread starter
7 Apr 2021
Hi. I’m scoping out a new 240 L tank and was wondering if a Fluval external 307 filter was sufficient for adequate flow in that tank? Thanks
Hi, the answer depends on your future plans/aims. Are you planning co2 and high lighting or non co2 route?
The 407 gives a quoted circulation of 1450 litres per hour. Which is under the recommended 10x rule that is usually aimed at for a planted tank, of course there are ways to bump up the flow like using a powerhead or skimmer for example. Your plans for the tank make a big difference in the turnover required.
A lot depends on whether your are going to inject CO2. If you are, more flow would be better, - not necessarily more filtration, as you can use powerheads or wavemakers to add flow.
Without injecting CO2 it's more a question of what you are going to keep in the tank.
Thanks for these replies. The tank will be quite heavily planted but I haven’t yet made up my mind about Co2 injection primarily because I haven’t done my homework about that yet. Any preliminary thoughts gratefully received.
Hi Robert,
I have two 240l tanks, both low tech. I started out with the 307 on both tanks and the flow wasn't sufficient. I ended up adding wave makers to both tanks which supplied another 500lph of flow and for a while that worked out well.
As the the tanks plant mass increased it became increasingly difficult to get a decent flow around the tank and I upgraded one of 307's to a 407, this gives a far more controlled flow, but I still use the wavemaker alongside it. I will be upgrading the other 307 in the not to distant.

A lot depends on what outlet orientation you end up going with but for me pushing the water down a 4ft tank isn't easy and would suggest at the minimum you go for the 407.
Should also add that I think both the 307 and 407 are good reliable filters.
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Thanks John for this helpful advice. It's definitely going to be the 407 for me. I should add that I'm probably going to go for CO2 injection. I know that the Fluval 307 and 407 are both reliable filters. The tank I am hopefully going for is a Fluval one that comes with a 307, but I had heard that it wasn't quite strong enough for a 240 L tank, hence my query. If I go for it I will see if the retailer will swap out the included 307 for a 407. Thanks again to everyone who replied. It was very useful.
If you're going for the roma 240, that's what I have btw, and plan to eventually use co2 I'd probably try and upgrade to the fx4.
The twin outlets as standard on the roma can be difficult to master and the option of more oomph from the fx4 will certainly help.
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John, thanks, that's very interesting. Upgrading to the fx4 is certainly possible especially since it is a new Roma 240 I am aiming for. Do you know if the fx4 connections fit easily with the new Roma 240 connections, and does the fx4 fit well inside the new Roma 240 cabinet? Sorry to ask.
No worries, yes the fx4 will fit inside the cabinet, its a snug fit and you'll have to remove the water changing tube that's wrapped around the filter, but it fits and the door will fully close.
Before you install the through pipe connectors you'll notice they have tapered tails at the base, just cut the 16mm tail off with an hacksaw and the bigger dia pipes will fit the larger remaining tails.
This link explains the connection mods in more detail. I mention in this post that the pipe I'd is 21mm, it could be a tad bigger than that but it still fits regardless.
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