View Full Version : Flow and Turnover?
Hello guys,
I am planning a small 32"x27"x27" reef aquarium, eco-system MM sump style.
Sump would approx be 30"x18x18... waiting for quotes over possible size.
I have heard different views on turnover in sump and how much you need.
If sump flow is supposed to be approx x 5 an hour, for a system that will hold approx 350 litres of water, would a 2,000 lph return pump (like the Eheim compacts) be the right size or should i aim higher?
Also i am a little confused over flow and turnover. Do powerheads contribute to turnover and is it a simple cumulative calculation xlitres + x litres, or do they just contribute to circulation in the main system?
So sum of powerheads + return pumps = main tank circulation and only return pump rating = sump turnover.
Am i right in thinking the circulation in the main tank should be in the order of x20-30 total system volume?
Thanks for any help. :)
Hi Sanj
System, or sump, turnover is based solely on the volume of water that passes through your return pump, so yes your initial thoughts are correct. However, it is usually bettter to over do the return slightly, as head loss will reduce the effectiveness - in your case, the 2000lph could in reality be around 1200lph, so aim for closer to 3000lph IMO.
In tank, or display, turnover is calculated as a function of all the devices in the display that move water (excluding mave boxes IMO, as they cause oscillation rather than flow). 25-30x per hour is a good starting point - brisk, turbulent flow is the answer, minimising any dead spots within the tank. I tend to aim for the turnover figs from powerheads alone, and any extra that comes from the return pump is then bonus.
aquadorge,
Thanks for the reply, you seem to have a system of a similar size ot the one I am planning. I was thinking in the region of 3000 l/ph return pump just that i was not sure what would be too powerful a rating for the MM sump.
No, I think it would be fine - when I see how much oomph is lost by the time it gets to the tank, I certainly wouldn't want to go much lower.
If going MM, then make sure you can devote as much sump space as poss to the mud bed for it to be effective. A larger surface area with a couple of inches depth, is better than a small suface area with it several inches deep.
What algae do you intend to use - Chaeto or Caulerpa?
if you go cheato make sure that you put a pair of stockings over the pump so you dont get bits in it as this is what made my first powerhead die
No, I think it would be fine - when I see how much oomph is lost by the time it gets to the tank, I certainly wouldn't want to go much lower.
If going MM, then make sure you can devote as much sump space as poss to the mud bed for it to be effective. A larger surface area with a couple of inches depth, is better than a small suface area with it several inches deep.
What algae do you intend to use - Chaeto or Caulerpa?
Hi, yes at the moment i am thinking about that, I have asked the people I am waiting on quotes for to make the mud bed area as large as possible.
The only thing i was thinking was the future (if needed) space for a skimmer. Could i easily place a hang on skimmer on the sump, if no room in the actual sump?
I was thinking the surface area of the mud bed to be at least approx 1/3 of the area of the main aquarium?
How wide does the first and last chamber need to be in a basic sump design?
I thought 6" in the last chamber, but not sure about the first.
No real size restraints, the only consideration needs to be if the final chamber is large enough to hold your return pump. Also, the smaller the final chamber, the greater the impact that evaporation has on the level, so an auto top-up is an essential IMO, when the final section is on the small side...
As for a skimmer, if your MM system is properly set up and balanced, then you should have no need for one - friend of mine is running a similar vol tank with MM and his bed size is similar to yours, he's getting great results. His 'tip' is the regular hard pruning of the algae bed, by stripping 60-70% of the algae every 10-14 days or so, he has kept his nutrients well down and his corals are flourishing.
Thanks again, I am going to include a top up, not sure which model, but what you said makes sense.
Does your friend also keep SPS/LPS in his MM Aquarium? how long has his sytem been going.
Some people have suggested that it would be difficult to keep SPS although seems Frogfone (?) aquarium was growing them very well (March TOTM).
I am going LED though whihc may/may not be a limitation. Heard mixed reports.
Thanks,
Sanj
If you want to keep SPS, then LED's will not be sufficient for a start, they're simply not strong enough at the mo. My friend does keep some SPS, but they aren't doing as well as his softs and LPS do but it could be allelopathy from the softs rather than anything else, hard to determine exactly why.
If it's an SPS system you are after then for me, a monster skimmer would be a better sump component than a MM bed.
hello, I think I will start out with soft corals and LPS. I was just wondering about the SPS, although I thought there were some varieties of SPS that do not require as bright light.
flow is affected by the type of corals you want to keep, sps tend to want 25-30x ttank volume, softies and LPS will be happier with 15-20x depending upon type. More importantly is where the flow is. there's two vital areas IMHO.
1. surface movement, with no skimmer it's easy for oil and dirt to accumulate on the surface of the tank, this affects light penetration but more importantly limit's gas exchange.
2. under live rock, if detritus does not get into the sump than it does not get broken down and consumed efficently, eventually it starts to leach nutriants into the system in great quantities than the sump can cope with.
a decent sized powerhead under the rock is the easy answer.
for the return pump over estimating is a good idea. the eheim compacts can be throttled back anyway and a 5' head can really reduce smaller pumps.
Montipora's tend to do well under lower light, esp green and red ones.
Roddy
Thank you Roddy,
Montiporas are they those large plate like corals. They look really good.
In regard to the powerhead under the live rock, do you mean the rock is built around and over the powerhead so that it is inside the mass of live rock or just placed down low in the aquarium and blowing into the rock mass from outside.
Do you think two powerheads are enough for my size aquarium or more?
Thanks again.
Sanj
montipora can be plating or branching the plating is more common type. the branching type is called montipora digitata.
the powerhead is placed under the live rock but in such a way that you can access it by removing 1 or 2 rocks.
ideally you should have all your rock on eggcrate which is raised above the glass and then surrounded by a skirting of some sort. you then position the powerhead pointing towards the bottom. the flow should then be nicely diffused through the rock which stops detritus building up and keeps the rock nice and clean. It's basically a poor mans reefclean system. there's quite a few example's in the tank build section.
two powerheads should be fine in addition to the return pump. 1 under the rock and one crossing over the retun flow to cause maximum turbulance.
Obviously will depend on the poweheads. i would aim for 20x turnover just now. if you decide to go more SPS then a third powerhead would be all you would need.
Roddy
Thank you again Roddy, very helpful.
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