# Increase flow rate without creating a whirlpool?



## LancsRick (22 Jun 2012)

I hooked up my two Eheim 2217s last night (and initiated myself into the external filter camp of "mouth of fish water"), and I'm hugely pleased with them. Given that I have a 190l tank (Trigon), I was expecting to need both of them in accordance with the 10x flow rule.

With a single filter running (intake at rear apex, horizontal spraybar on front glass facing rearwards), there appears to be flow around the entire tank (I kicked up a load of mulm deliberately to get a visual representation of the flow). This is only 5x my tank volume though, so I then kicked in the second filter, with the intake at the same place, and the output as a horizontal spraybar on one of the straight sides of the tank, cutting across the flow of the first spraybar at 90degrees. Unfortunately this turns my tank into something resembling an underwater gale, and it really doesn't look beneficial for either plants or fish!

So, the question is this: What is the best way to preserve flow throughput, whilst not setting up a whirlpool in the tank? Physically I can't see how this is possible, but there are smater people than me here!

Alternatively, is the single filter enough if I appear to be getting steady flow around the tank?

Cheers!


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## Tom (22 Jun 2012)

Spraybars (or multiples) with large holes. Recently did this for my 4' Goldfish tank as they couldn't cope with the flow/velocity. Drilled out the holes on the Eheim spraybar kit slightly and it's much better. You'll probably get a slightly better turnover as well as there's less restriction.


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## ian_m (22 Jun 2012)

I saw a Trigon 350 tank in a fish shop the otherday, they had two external filters feeding spray bars at the front of the tank. The pump inlets were at the front as well, one in each front corner, rather stood out.

The top of the tank had been cut to get water pipes in and out. Pipes draped down sides of tank, slight unsightly I thought.

The spray bars had been cut and joined with short lengths of PVC tube to make them curve round the front.

Looking at the Trigon manual, and if I had one, I would have placed the two spray bars along the sides of the tank, making use of the tank cutouts to get pipes in. I would place the inlets at rear of tank below the cutouts. Means no cutting of spray bars, to make corners. Hopefully all pipes at rearish of tank and not visible.


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## LancsRick (23 Jun 2012)

Thanks for the feedback guys. I'm trying out configs atm in preparation for stripping it down tomorrow - I'd be grateful for a view on the video below please.

I've drilled out the 3mm holes on the spraybar to 5mm, which has avoided making a whirlpool, but there's still a lot of movement and I'm wondering if this is too strong for livestock? I've never had a high flow tank before so I don't have an appreciation for what the upper limits are. I realise I still need to tweak a bit since the plants at the rear are getting blown around way too much.Thanks!

video


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## LancsRick (23 Jun 2012)

I've just tried the layout suggested by ian_m, and it looks like I could have a winner! (Yes, the tank is a mess, I'm trying things out prior to strip down so I know what I'm doing then!

http://www.youtube.com/watch?v=ipbaTe4hhV4&feature=plcp

I presume the problem I had before with too much plant movement would have been down to crashing two flow patterns into each other, pushing the water straight down as a result. Doing a "normal" straight spraybar config seems to still work even in a corner tank like this.


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