how many times a hour should the water go through the sump?
 

just wondering how many times an hour should the tank water go through the sump? 1? 5? 10?

I would aim for about 3-5x per hour.

If you have selected the correct skimmer and the flow in the tank is moving the water towards the overflow box then.. 2 or 2 1/2 times max.

There is really no set amount, slow or fast both work the same. Mine is set at about 800GPH swap over or almost 5 complete tank volumes.

Why a max of 2?

Actually skimmers work best at a 1 times turnover, that's how they are designed, beyond that they become less efficient.

I was waiting for someone to make this argument, please explain to me why that would be?

If a skimmer draws in water @ a set rate which is completely unrelated to the water movement around it then why would slowing that water down increase its efficiency?
Levi

It's quite simple, if you run a lower turnover rate the water(containing surfactants) coming from the overflow box is concentrated rather than being 10% crap and 90% water in a 10x rate, the skimmer does a far more effective job with a concentrated solution than a diluted one.

By that logic, the same amount of water would pass through the skimmer would it not?

Theoretically:
1gph=100% skimmed
10gph= 10%/gal

I dont really have a preference. As long as water gets skimmed its a win situation.

If you skim it 100% then what you return to the tank is clean, if you skim 10% of it then 90% of what you return is dirty or unskimmed, why would you do that when it costs more money in hydro and pumps to do worse?

I understand that. But say, someone was using there return pump for extra flow to their tank. The extra water movement through there wouldn't technically affect the skim-mate that is pulled out of the water.

That being said, there is no actual way to test out these theories as a skimmer pulls out skim-mate in both situations. This test would be almost impossible because everyones tank (or say a "test tank") would differ from one another so getting a control would be practically impossible. I am not saying your opinion is wrong/invalid , I am just saying that in my opinion the flow rate through your sump isn't a big thing to lose sleep on.

I would hate you to lose sleep, however the flow past the skimmer is directly proportional to it's performance.

From my first post I mentioned that PROVIDING the flow in the tank is moving correctly then a 1 to 2 times turnover rate is more than adequate and anything else id disadvantageous.

If I give you phone numbers for the top ten skimmer manufacturers would you call them and tell them they are wrong?

Just a question to you, do you think that a 10% water change done everyday is the same as a 100% water change every 10 days?

When it comes down to it a sump has more uses than placing your skimmer in it, extremely slow flow could invoke negative side effects for your reactors, heaters and makes filter socks practically useless.

Do you have any articles that I could read that would sway my opinion? I understand your logic but in a practical setting nutrients are not only on the surface and increasing the flow allows proteins that are dissolved to be removed.

No they are not the same. My comments were not made as an attack, which it seems to me is how they were taken as per the condescending tone in the last post. I understand that slower flow would result in better skimming due to less dilution from mixing the skimmed water with the DT water. that is also an example of your water change remark. a 100% water change is a lot different that 10%/day.

I were merely stating my opinion and am done on the matter. Anything else feel free to pm instead of filling up the boards.

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These theories are all based on the idea that your sump is a filter. While it may seam that most of the water cleaning devices people use are situated in the sump, this doesn't make the sump a filter. It's a place to house filtration equipment. I view my tank, my sump, my refugium and all of the plumbing in between as 1 body of water. So to me it doesn't matter how much flow goes through my sump because my skimmer would work the same down there as it would hanging off the side of my tank, or in my refugium.

As Levi said, the skimmer works at a set rate so it shouldn't matter how much flow is churning around it.

In what way could they be problematic how would a filter sock become useless

what should the flow be through the following?

Refugium
UV filter
Charcoal filter
Phosphate filter
Water polisher
etc etc etc.

all are very low requirements, other than the possibility that the skimmer MAY work at 10 times turn over why would you do it?

That part of your statement is not true it would work better under lower flow circumstances,
it would be more effective hanging on the back of your tank than being in the sump with a 10x turnover rate.

I answered a post, I was challenged with my answers and replied to the questions, I would be happy to PM you so the boards are uncluttered, but why?

PM sent

so did my thread just get hijacked?
all i wanted to know was should i buy a 1325gph pump or a smaller one, lol

Buy the smaller, cheaper, practical, more efficient one.

The filter sock would loose efficiency because it requires high flow to capture as much particulate as possible. You keep restating your point, your logic is understandable but I need some concrete proof (And no I'm not going to call Euro reef and ask them) before I believe it.

The reason I don't believe you is because I own a skimmer, I have 7X turn over in my main tank and still get a very large amount of skimmate production.

If I slowed the flow down even more to the sump would I get more concentrated skimate...? I highly doubt it, again nutrients don't only exist on the surface they are mostly found dissolved in the water column. Considering that letting your skimmer have more access to the polluted water makes more sense.

Ha! thats why i love science. Its all conflicting theories. :lol:

It makes for some good debates. I would say any pump between 500 GPH and 1300 GPH will work for you, draw your conclusions off of what people have posted.

It does? how does that work, it is a filter, why so much flow the water falls out of the overflow box at a constant unless you are running a siphon ?


As Jack Nicholson would say "you can't handle the truth"

as compared to what?

Of course you will, if you slow it down by half the surfactants delivered to the skimmer will be double in the same time frame


That is the point.

Water flowing out of an overflow box is proportional to the amount of water going into your tank... from your return pump, as that level increases more will flow out of the overflow box. More flow through a filter means that more particulate will be captured. This is a very simple concept, no need to be snarky if you can't understand it.

I'm not touching that one...

As compared to not getting any skimmate at all, If I didn't have positive results out of my skimmer I would assume something is wrong. I'm getting positive results so I'm assuming my mode of skimming is correct.


Magically more surfactant is generated because less water is getting to the skimmer? Do you read what you write before posting?

This is my last post on the topic, as I don't enjoy arguing in circles.

I was going to say just let it go. Our PM's have followed a similar path.

I may as well talk to a couch....

Or two couches for that matter :neutral:.

la di dah. just make sure it doesn't slow down to a trickle and not too fast that the equipment in your sump are tumbling around.

I was with you up until this post, and that's mostly because I was having trouble understanding both sides until now. However, a tank + sump is a closed system. The amount of water running through the sump should be irrelevant. It would be the same as a HOB skimmer running in a sumpless tank with 100x turnover using just powerheads. In this case, the DT is just like a big sump (since there is no sump).

Water in the sump is the same water as the DT. There is no special separation between the two except the OF, a pump, and some pipe.

The concept that "a sump is not a filter" is a good one. A sump really is nothing except a place to store equipment.

Now if your argument is that a low-flow overflow extracts surfactants better, perhaps you can discuss that more.

To the OP, I believe the recommended rate is ~5x but this is only what I read.

"I saw it on TV so it has to be true!"

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That's what I said only in different words. Not to kick a dead horse, but the skimmer controls its own rate of flow through the body of the skimmer. In which case slower is better for extracting surfactants, but only within the skimmer itself. The higher the contact time between the water and the bubbles, the more effective the skimmer is at pulling out waste. This has nothing to do with the rate of flow through the sump, tank, fuge etc.

Find whatever flow keeps everything the most silent, don't worry about anything else :mrgreen::mrgreen:

That is the whole point Mike.

Firstly we all have overflow commonly called prefilter boxes...Why call them this?

Because they are moving the surface water only from the tank when done properly, If you imagined that fish waste, coral waste and detritus was similar to oil it isn't hard to visualize oil floating on the surface of the DT, the prefilter box is there to remove it, the slower the removal the more concentrated that would be , if the extraction rate is increased the oil is mixed with more water and becomes diluted.
So this oil/ water mix then goes to the sump where some use filter sock for containing large bits etc, it then should enter the skimmer as concentrated as possible and then the skimmer can do it's job properly.

Why anyone would want to keep returning dirty water continuously back to the tank so they can keep skimming a little at a time is beyond me, get it out get rid of it and return clean water back to the tank.

I've always thought of it this way.. imagine that there is one car wash in the city and all the cars have to go through it. The car wash can only service cars at a certain rate, say 5 cars an hour? Unfortunately the cars can only wait at the car wash for so long before they have to move on (that is they can't sit there forever and wait), so cars are moving through the car wash at a certain rate independent of how fast the car wash can wash cars. As cars come in they get washed, or if they've waited for too long they move on and don't get washed. If cars come in very quickly, obviously fewer will get washed and will just end up passing on through unwashed and so the dirty car ends right back on the streets. If the cars come in slower at a rate that the car wash can handle then more cars will get washed. If it is a perfect day where the rate of cars coming in equals the rate of the cars being washed then all cars will get washed. Also, keep in mind that this is the only car wash in the city so all cars must eventually get washed, so eventually those dirty cars that had to pass through unwashed last time will eventually come back and try again to get washed. The faster they can turn around and get off the streets and come back to the car wash the better their chances of getting washed within a small time frame, but that also means they can't spend as much time at the car wash.

Agreed.

Slowly we can see the use of closed loops falling out of favour because of the high energy costs and a number of other reasons (tank wall integrity, OMs, maintenance, etc). That leaves powerheads and propeller pumps. Many people, a long time ago, decided they preferred to not have PHs in their tanks long term, if not for the appearance, then for safety. That leaves propeller pumps which are very costly once you get beyond, well, one. For this reason I think we will see large volume returns continue.

I don't use a pre-filter so I have nothing to add about that. I do use filter socks but that's just to reduce bubbles in the sump.

I'm gonna use the same car analogy. Going too slow means you are burning all the fuel that goes into the engine but you are not utilizing all the energy that the car is capable of, going too fast and you are not burning all the fuel that goes into the engine. In either case you need more fuel to get to where you want to go. The sweet number according to experts if I am not mistaken which they say would be fuel efficient would be between 60-80.
In a way if you have a tank that is 100 gal and you have a skimmer that has a pump rated at 800 gph and you have a turnover rate of 1 that would just mean that at least the same water goes through the skimmer 8 times. If you have a turnover rate of say 40 that would mean water would just be passing from your tank to your sump without even going to your skimmer. It you go around say 4-8 then the water would at least pass through your skimmer at least once or twice. I think that would be efficient enough. Going too slow and you are just going through water that has already been stripped of all those waste and oil and going too fast and you are not getting stripped at all.
Same thing with the heater if you have it in your sump. If it is too slow then the water is not heated up with evenly, if it is too fast then the water just passes through it without getting heated up at all.
best way is to just match the capability of your equipment with the turnover rate of your tank to your sump otherwise you are either wasting energy either it is just being redundant or not doing the job at all. It is going to be a trial end error thing but you will get the feel for it as it goes along.

Except that the sump isn't a separate unit; the tank and sump are the same system. The turnover rate should be a non-issue. What is important is that the overflow box is large enough to handle the volume going through it. If your OF is 10' long and is able to extract the surface of the water and not just a lot of water, it is running efficiently. This means you could have 1000x turnover in your 20 gallon tank. The amount skimmed off the surface, whether 10% or 100%, removed by the skimmer is a non-issue because the skimmer can only handle what it's rated for.

I think the issue here is redundant recycling of clean water, not turn over.

This whole argument is theoretical.

Am I going off topic here? The poster was asking how fast the turnover rate is suggested. And so is the analogy I was putting in there. A car is not separate from it's engine either. It may not be separate from your system but it contains a lot of your equipment. It may or may not be that the skimmer might be efficient with a slower turnover or not, believe what you want until a thorough study comes out about it. The skimmer isn't the only equipment in your sump some of them do need some lingering time to work efficiently at the same time they won't work well if the water was almost not moving.

The opening post asked about sump turnover,not tank turnover. whether you like it or not if you have an overflow box you do have a prefilter box they are technically doing the same thing, why are people saying as I said years ago that having no teeth in the oveflow box is more effective? why because it skims better.

There might be an ideal turnover rate if the skimmers were 100% efficient but doubt they're close. Even if they were, what's the big deal if one decides to have the return pump contribute to the overall turnover of the tank. Really, if one could accurately measure waste remove by our little hobby skimmers, would there be a significant difference between 1x, 2x, 5x flow through?