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Flow In A Large Low Tech Tank

James O

Member
Joined
16 Nov 2013
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891
Location
South Coast
I'm a planner, and so like to cover all the angles befor I set sail

Project details so far are:

Large tank - 183x50x50 pending spousal approval, but definitely tightly in this 400l region

Low tech - I've been playing around with LC but I'm not really seeing much benifit between tanks with/without

Filtration - I'm going to run 2x Eheim 2217 with DIY prefilters. Inflow at one end, outflow at the other.

Scape - lavarock & redmoor heavily planted with various anubias, bolbotis, java ferns, moss and swords

Wildlife - a generous smattering of rainbows, denisonii barbs with a large otto & amano shrimp cleanup crew

Water flow is my present brain teaser. As this is low tech I don't need CO2 tank levels of flow but I know I still need movement to keep detritus moving to the filters and to transport ferts around the tank etc. I'm not planning to use the Eheims for flow, other than what a simple shepherds crook or similar can produce. This will give me longer filter cleaning intervals as flow won't be reliant on filter output which obviously drops with buildup.

My options as I see them are: pump attached to full length spraybar, or, powerheads (koralia etc)

What would you guys do?
 
I would try to create an even laminar flow from one end of the tank to the other, there's a new pump in market specifically for that. Can't remember its name though!
 
What turnover will your filters give you James?

In theory 1000lph each, so up to 2000lph total. They are specced up to 600l tank each but I think that's optimistic and so two on a 400l tank is plenty. I'll be using them 1/2 to 3/4 full of pan/pot scrubbers as I've found these allow plenty of biological filtering and great flow. This will be helped by the prefilter (aka open cell foam wrapped around the inlet) doing most of the mechanical filtration.[DOUBLEPOST=1404910280][/DOUBLEPOST]
I would try to create an even laminar flow from one end of the tank to the other, there's a new pump in market specifically for that. Can't remember its name though!

Is it that maxspect horizontal cylinder fan type contraption? Might be a bit blowy for a planted tank as it's aimed at the marine market I believe? Those balls being flung round the tank was impressive. I wonder of they do a little one?
 
I'd personally have double that in filtration for that dimensions and size tank. Forget about whether it's co2 or non-co2 tank and aim at 8-10x in filtration. These two 2217 will barely cope with the tank once you stock it and feed it as per the size allowance, plus them slowing down before each cleaning and the small volumes those filters have.
 
Really?!? 12l of filter medium won't be enough :eek: :arghh::wideyed:
 
Really?!? 12l of filter medium won't be enough :eek: :arghh::wideyed:
Thats what i thought. I would have said a planted tank would be fine with 12l of media. Flow doesn't really drop off with the 2217 either, even when its filthy and rammed full with media it only slows a bit. Make your hoses as short as possible this will give you much more flow. Long hoses restrict flow much more than lots of media.
I would think about more flow too, power heads supplying custom spray bars is easy and cheap but you do need to hide the pumps
Finally dennisonii are good jumpers, mine sometimes chase each other out of the water when sparring so heavy covers are advised

Ps i hope mrs o approves
 
Mrs O is in full accord. Mostly because I'll just have 1 tank rather than 4 in our lounge :D Bargaining power ;)

Yes I'll need more flow. A spraybar with a waveline or jebao 3000lph pump running at 60-70% would be enough but 2 or 3 koralia type heads give me more adjustment (aim and individual flow rates/patterns) depending on scape layout etc. I like the look of the new eheim heads....

But which way to go? Both are about as expensive. More powerheads means more flexibility. Pump for spraybar would need to be hidden & cleaned but seems the standard.

I dunno.....any ideas?
 
Yeah, perhaps it isn't optimal - though I don't see the problem - but to say two 2217s would "barely cope" with a stock on a tank that size is nonsense. As Big clown has pointed out, the flow doesn't drop off much on these filters, either.
 
Yeah, perhaps it isn't optimal - though I don't see the problem.

Blimey :wideyed: How much filtration 'should' I have then?[DOUBLEPOST=1404932908][/DOUBLEPOST]
Btw, have a think about a sump, works like a charm, especially without CO2;)

Oh the very thought of a sump makes me warm and fluffy- I love the 'idea' of them :joyful: But I'm terrified of leakages :drowning: I've read up on durso, bean animal etc and the advantages are HUGE. I fear leaks and the extra weight, on top of the 400kg of water, 50-60kg tank + stand. I'm on the first floor:(
 
Blimey :wideyed: How much filtration 'should' I have then?

I meant 'optimal' in the sense that any combination of filters with a larger capacity and a higher flow-rate would be better. I really don't see the problem. You're using two quality filters rated at 600 litres each. You're over-filtering. You can add more flow in the form of powerheads or whatever, but you absolutely won't need more filtration than two 2217s on a tank that size. You just won't.
 
I'm not actually using the filters for flow at all. That's what I can't decide, powerheads or spraybar? Filters are purely for filtering
 
Oh the very thought of a sump makes me warm and fluffy- I love the 'idea' of them :joyful: But I'm terrified of leakages :drowning: I've read up on durso, bean animal etc and the advantages are HUGE. I fear leaks and the extra weight, on top of the 400kg of water, 50-60kg tank + stand. I'm on the first floor:(

Don't be afraid of leakages, if it's done right that is :D:nailbiting::lol:

As far as weights concerned, the sump is normally only run at half capacity anyway (to cater for any water left in the weir should the return pump fail) so even a 100l sump will only be around 50/60 kg extra (plus the tank) Not much anyway in the grand scheme of things. Go for it.

Good luck with the build anyway, whichever way you decide to go :thumbup:
 
You're using two quality filters rated at 600 litres each. You're over-filtering.

Overfiltering? That's 2 filters, 600l/h each on a 450l tank, that's 2.67 the tank volume an hour. I think that's hugely underfiltered.

Edit: Oh, sorry, my bad, they are 2000l an hour between the two, so it's 4.44 times the tank volume an hour, still underfiltered in my opinion.
 
But higher speed of flow across/through filter media doesn't equal better filtration. Possibly the opposite
 
I've got 2x flow running through mine and to be honest it is spot on. I did actually want more when I was planning, probably 4x I originally had in my head, but due to head height I've lost near enough 1500lph off my pump. I'm heavily feeding I suppose (young discus & beefheart 5 times per day), but 15 minutes after feeding the water is back to normal, no small particles and clear again.

I think people might start confusing flow rate with the filtering rate. A slower flow through the filter is going to be a lot better than water flying through at speed IMO High flow is going to force far more bits through than one flowing slowly, obviously ending back in the tank eventually, possibly. The water is also in contact with the bio media for a lot longer. As long as the actual flow rate in the tank is strong enough and keeps everything in suspension, the filter will eventually pick it up no matter how slow it's rate is.
 
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Overfiltering? That's 2 filters, 600l/h each on a 450l tank, that's 2.67 the tank volume an hour. I think that's hugely underfiltered.

Edit: Oh, sorry, my bad, they are 2000l an hour between the two, so it's 4.44 times the tank volume an hour, still underfiltered in my opinion.

It's not, though. I've had two 2217s on a 450 litre tank that was packed full of 4" mbuna. I had roughly 40 of them in there and they are messy fish. People say you should aim for 10x turnover but that is in part due to certain brands of filters only really supplying 50% of stated flow. I've run a lot of practical tests with external filters. On this 450 litre mbuna tank, I went through an FX6 (rated for 1500 litre tanks, but given your own criteria one of these wouldn't be fit to filter a 450 litre tank), two Tetratec EX1200s and two Eheim 2217s. All of them performed well but the FX6 was the worst out of them (despite having the best actual flow-rate). I put this down to the limited capacity compared to the other combinations. I found a couple of litres of a high quality sintered glass bio-media divided between the two filters was enough to deal with the bioload. That then left me with 10 litres of mechanical filtration. My water was crystal clear, every parameter was as it should be, and for extra flow I just used wavemakers.

Sorry for derailing your thread, James. To take it back to the topic I'd recommend the Tunze Turbelle range for water-movement. Like your 2217s, they're energy efficient and no fuss.
 
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