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|01-04-2010, 07:58 PM||1|
All about Sumps Filters and Fuges
This subject comes up a lot, so I wanted to go over some basics so we are all on the same page. These components get blurred as to their functions and lay outs. I hope this will alleviate some of the confusions and help you put your own system together.
A sump is a separate vessel below the main display tank. The purpose of it is to remove your equipment from your display tank and move it out of sight. It is also a good way to better utilize the space under the display tank. A sump allows bigger better skimmers, more room, and added volume for the system. All a sump is, is a vessel to hold water. Water is overflowed from the main tank to the sump, and then pumped back up using a return pump. It can be a simple open tank with no baffles, but there are other features that will want to be added. I won’t go into the various overflows, but it is important to add that the water overflowing the main tank is only supplied by the return pumps. There is no need to balance anything. Water pumped up overflows and drains back to the sump. If the return pump loses power, the process stops.
Water that overflows has air in the line. When it enters the sump, there will be bubbles and noise. There are various ways to deal with this. Some use rock rubble to break it up, some use filter socks, some put devices on the end of the drain…ect. All you need to know is that there will be plenty of air. It will need to be dealt with some way to minimize splashing, salt creep and noise if this bothers you.
I will discuss filters later, but just know that lots of people like to filter particulates out using various filter floss and filter socks. Filtering particulate matter and detritus from the display tank will help keep the sump clean of accumulation.
One of the big advantages for sumps is the ability to run bigger more efficient skimmers than Hang On Back models. You need to know what skimmer you want and what it’s foot print will be in the sump so you can fit it. Ideally, the skimmer section should be the first section in the sump. Raw water from the display tank should be fed to it first so that it can do it’s job of removing particulates and dissolved organics. It should get the dirtiest water, not the cleanest. Plenty of people do choose to filter this water first with mechanical filter as mentioned above. More on that later.
No matter how well a skimmer is adjusted, at some point micro bubbles are inevitable. These micro bubbles are pumped back up to the display tank and can be quite unsightly. Some sort of bubble trap needs to be employed after the skimmer section to prevent this. One way is to pass the water through a sponge of some sort. Sponges though can get clogged and reduce flow. Another way is to use 3 partition baffles to direct the water flow under and over them to get the bubbles to the surface. A very common way is to let the water overflow a solid partition. This forces the bubbles to the surface where they can break. Next the water is directed down. Most bubbles do not want to do this. The water flows under the baffle by a space provided at the bottom then up again over a third baffle. Once again forcing any remaining bubbles to the surface where they can break.
You can use two partitions, but they are not as effective. If you do, just be sure to pass the water under the first one at the bottom of the sump and over the second one on the return section side. That way the bubbles are kept at the surface away from the return pump suction.
One thing to remember is the skinnier the baffles, the faster the water will flow, and the easier it is for bubbles to be swept along. I would consider 1" minimum. I set mine at 1.5" for 3" total.
One advantage to using a partition bubble trap is to set a constant water level in the skimmer section. Most skimmers need a constant water level to provide consistent performance. The first or last baffle sets the water level depending how you have it configured. The depth of this section should be deeper than you skimmer needs. You can always move your skimmer up using a stand, but once the baffle is there, you can’t make it deeper. The point is you do not want a shallow section in case you should get a different skimmer.
The return section houses the return pump to gets the water back to the display tank. If you used a partition bubble trap as mentioned above, it is important to know that all your evaporation will be lost in this section. The display tank will overflow whatever water is supplied. The skimmer section is a constant level set by the baffle. Any evaporation throughout the day will be lost in the return section. So it is important this area can lose a day’s worth of water before you come home after work and top it off. Obviously, this is where you would want to place an automated top off system (ATO). It is important to understand if this section goes dry, or your return pump sucks air, you could be buying a new one.
Some folks choose to return some of the return pump discharge back to the sump. Instead of throttling the discharge, they run it wide open and adjust the flow to the display tank by diverting a portion back to the sump. I see no reason to do this. It is a waste of power and it does not harm the pump in any way what so ever. However, if you worry about running your return section dry, this is a legitimate way to ensure you will always have circulation through your return pump. I don’t do this, but if you are inconsistent about your daily top offs, or are gone for a long period of time, this is at least some insurance to protect your return pump. That is still not a good excuse to not top off, and an ATO is a good solution to the problem.
Sumps are a good place to put heaters. You can put them anywhere they have good flow, skimmer or return section. Make sure though that if you put them in your return section, that they will always be covered with water. I have an ATO, but this reason alone is why I choose to put my heaters in the skimmer section.
Various media reactors can be placed in the sump, either internal or external to the sump. One consideration is to have it take a suction after the filter and skimmer. That way they stay clean and do not get clogged up with detritus. Bags of carbon can be placed in the return section, just make sure nothing is loose to get sucked into the return pump.
Chemical dosing can also be accomplished in the sump. I use an automated pump system to dose chemicals. I put them in the return section. It has a nice high flow and is put right up to the display tank.
Other Important Considerations
The most important thing to understand about sumps is what happens when the power goes out. Whether the power goes out, or you turn off the return pump, all the water from the display tank will be drained back to the sump. How much water that is, is determined by how deep your return lines go into the tank. Water will siphon out of the display tank via the return lines. It is imperative siphon break holes are drilled in your return lines. Just below the normal water line is best to prevent any splashing or salt creep. This way the siphon will be broke when the water drains below these holes and minimize how much water is drained to the sump.
Regardless of how much water that is, it is critical to leave enough room in your sump for this amount of water. We want to use a sump to increase water volume. The sump and baffles can be as deep as you like to increase your volume. However, you have to leave enough room so the sump does not overflow on your floor when the lights go out.
Just what are Filters
A filter is a way to remove a specific contaminate by a particular means. Wet and Dry filters became popular, and afterwards sumps were sort of referred to as filters. A sump is just a vessel. A filter can be a component of a sump, but it is not what a sump IS. I will not go into the Nitrogen cycle, but if you are new to the hobby, it is important to understand what that it.
The Nitrogen Cycle - The Free Freshwater and Saltwater Aquarium Encyclopedia Anyone Can Edit - The Aquarium Wiki
Filters are classified by how they remove a contaminant. The filters we use in the aquarium hobby are mechanical, biological, or chemical filters. They employ these means to remove whatever it is we do not want.
These are the easiest to understand. They use various physical barriers to block particles. Oil filters on cars, filter screens in your furnace, vacuum bags are all mechanical filters. For our use we employ filter floss, or socks to filter our particulates. Those particles are namely detritus… fish poop. It is a personal preference how aggressive you want to get with this. When I first started, it was my line of thinking to remove as much solid waste as possible before it broke down biologically to add to the cycle. I don’t use any mechanical filters now.
The important thing to remember is that all that solid matter is food for bacteria. So we trap it and then provide a great place for bacteria to grow. If you allow your filters to get too clogged and leave them in too long, they will turn “biological”. Now when you remove them you remove a large chunk of your biological process with them. I’m in no way saying they should not be used, just be sure to maintain them properly. Since I don’t like a lot of maintenance, I just don’t use them. Well I do…. It’s called a skimmer.
A skimmer is a mechanical filter. There is quite a debate whether it is a chemical or mechanical filter. I’m not going to get into it here. Read the arguments for yourself and come to your own understanding. What is important here is that the skimmer removes solid and dissolved organics. When I took out my mechanical filters, my skimmer just picked up the slack. I clean my skimmer and no longer have the cost and maintenance of other filters.
Another mechanical filter is the RO (reverse osmosis) stage of a RO/DI unit. The RO membrane has pores that are only big enough to allow water molecules through. The bigger impurities are rejected.
Chemical filters use the property of chemical attraction to filter out contaminates. In our hobby, Granular Activated Carbon (GAC), Granular Ferric Oxide (GFO), Chem Pure, Rowa phos, are all examples of chemical filters. Another chemical filter is the DI (deionize) stage of a RO/DI unit. The resins attracts contaminates and remove them from the water. GAC attracts dissolved organics, heavy metals and other contaminates and binds them. Algae will release yellowing compounds into the water. GAC will keep our water crystal clear. GFO removes phosphates. Phosphates are fertilizer for algae, and also inhibit coral calcification. Low PO4 is a good thing.
Now that you are up to speed on the nitrogen cycle, we know that we can use living things to remove or break down contaminates. Bacteria break down ammonia to nitrites and others break down nitrites to nitrates. Those bacteria are oxygen loving bacteria. Oxygen hating bacteria can break down nitrates, but the two can’t live in the same place.
Wet/Dry filter uses highly oxygenated water to trickle down over some sort of media where those bacteria can grow and break down ammonia and nitrites. The ever popular bio balls. The bio balls are held out of the water by a plate where the water is exposed to a lot of air and trickles over them. This is a very, very efficient way to break down waste to nitrates. A little too efficient. There is quite a debate over bio balls being “nitrate factories”. W/D filters do not produce anymore nitrates than what you add to the cycle with food. Again, I’m not going there. Read the arguments and make your own call. What I will say is that a W/D filter is very good at it’s job. They do need to be maintained though to keep detritus from building up. This is the reason mechanical filters are placed above bio balls to keep them clean.
Other biological filters are macro algae. They are very good at taking up nitrates and phosphates. All they need are lights. Mangrove plants are another very good biological filter.
Perhaps the most widely used biological filter in this hobby is Live Rock. Rock taken off of reefs is very, very porous. The rock itself does nothing. What it does do is provide a huge surface area for bacteria to colonize. It is the bacteria that make rock LIVE. The awesome thing about LR is that it’s pores go very deep within the rock. Oxygen loving bacteria colonize these pores and break down waste to nitrates. They also suck up all the oxygen. After the oxygen is depleted, then oxygen hating bacteria can grow and consume the nitrates. Live rock is an excellent biological filter. The fact that it can remove nitrates is why it is a much better filter than a W/D filter alone. W/D filters release their nitrates to the water column and have no way to reduce nitrates themselves. Simply put, live rock is the best biological filter you can have for their ability to break down ALL waste to nitrogen.
Deep sand beds are another area that can be colonized by oxygen hating bacteria to break down nitrates. In fact, denitrating filters are nothing more than a very long tube in coils that allow bacteria to grow and deplete all the oxygen so the other bacteria can consume the nitrates.
Difference between Wet/Dry and Canister filter
Canister filters use a pump to take water from the tank and pass it through various filter stages. They use mechanical and chemical pads to filter the water. Filter media trap wastes and unfortunately provide a good place for bacteria to grow. If you do not change out your filters frequently, they will become colonized with bacteria. The bad thing is, when you do take out the filter media, you remove a large part of your biological filtration with it. Canister filters are efficient at filtering the water, however, they do not oxygenate it.
Wet/Dry filters employ filter floss and then a area for the biological filter media for the water to trickle over. Bio balls, or ceramic media such as rings. Not only is it a good place for bacteria to grow, it exposes a lot of water over a very large surface area. Therefore, it is very good at oxygenating the water and removing CO2. So it is beneficial to the gas exchange of the tank.
So what the heck is a refugium, and what does it have to do with sumps and filters? A refugium is nothing more than a refuge for pods to grow. Period, end of story. Hence the name. Pods will naturally grow in any reef tank, but the population is kept low by the tanks inhabitants. Everything eats them. So we provide a place free from predators so the population can grow bigger. This refuge grows a large population of pods. The pods reproduce and their offspring is swept into the return section and up to the tank. The coral feed on the larvae and we provide a natural food source for the reef. The only thing the pods require is some sort of habitat to nest in and be happy. We can provide that with simple rock rubble.
The fuge is a naturally good place to grow macro algae. All you need to provide is a light. Most folks use Cheato or Calurpa, but there are other macro algae’s that can be used. Mangroves are another good plant. The whole point is for macro algae to grow and suck up nitrates and phosphates to limit micro algae growth in the main tank. The algae also provide more habitat for the pods. A simple clamp on light is good enough. I use a simple 6500K 26w CP. Even good ole incandescents are good, but give off more heat. Keep the color temp between 5500-6500K.
Deep Sand Beds
A DSB is very beneficial to help remove nitrates by providing a low oxygen area for the bacteria to grow in. Some folks do not want to run a DSB in their main tank. A remote DSB can accomplish this outside of the main tank. A fuge is a great place for a DSB. It provides more habitats for pods and all the other micro fauna that grow in a sand bed. Most folks put mud in the DSB to leach trace elements back into the water column. You can use plain old clay kitty liter, or spend a small fortune on magic fuge mud. Bottom line is DSB have been shown to offer a host of beneficial factors.
Here is a great article on how sand beds work.
What’s the point….
A fuge is an excellent place to put all these beneficial components. Macro algae for nitrate and phosphate export. DSBs for habitat for micro fauna, trace elements, and nitrate reduction. And a place free of predators so we can grow a healthy population of pods for a food source for our reefs.
So let’s make a sump/fuge.
Let’s build on some of the component considerations explained earlier. A skimmer should receive raw water from the display tank. The fuge should also receive raw water. The waste in the water is food for the pods and micro fauna. The skimmer section should have a constant water level and bubble traps. The fuge does not need bubble traps, although you may want to use some sort of grate to ensure no macro algae makes it to the return section. The only way to provide both sections with raw tank water is to split the drain coming down from the display tank.
Flow through the sump/fuge
The pods in the fuge do not want to hold on to dear life fighting a 1000 gph flow. In fact, the fuge needs very little flow. Some say 10 times the fuge volume per hour. So if your fuge section only holds 10 actual gallons, then we are only talking about 100 gph. That is very little. Now some folks use higher flow, but even at 20x, that is still only 200gph. The waste will settle for food, the DSB will break it down, the algae will suck up the rest, and the pods can swim around no sweat.
The skimmer section only needs enough for the skimmer to process. Most manufacturers do not publish water processing rates of their skimmer. It is actually hard to measure depending on the air flow. My skimmer which can go up to 180g only processes about 400 gph of water. So again, no need to supply it with 1000 gph. I have probably less than 600 gph flowing through my return pump feeding my skimmer and fuge on my 90g tank.
If we split our flow to provide the different needs of the skimmer section and fuge, then that means the return section needs to be in the middle of the two. Both sections overflowing to the middle. Some folks do put the fuge and skimmer section "in line" next to each other for simplicity. However, there are problems with this.
If raw water goes to the skimmer section first, it leaves very little food for the fuge to feed off of. It will get some, but not much if you have a good skimmer. If the fuge section comes first, then all the pods and larvae that are swept out will have to make it past the skimmer. The skimmer will remove some of them. Not everyone agrees with this, but it makes sense to me. So besides the fact that the skimmer removes some pods, or the fuge does not get fed well, we still have the problem of too much flow. The entire return pump is flowing through the fuge section. Again, we want low flow. So there are problems with this approach. There are many that do this, just understand the trade offs if you decide to do the same.
One alternative is to put the skimmer and fuge section side by side on one end, and both overflow to the return section on the other end. It’s a reasonable approach, but more complicated. Placing the return in the middle is pretty simple. The problem only comes when you decide how to split your drain. One thing to keep in mind…. The drain line carries air and water. So it is not full of water. Why this is important is that if you split off say the top of a horizontal run, you will not get any water to the fuge. Try to supply the fuge off the bottom of a horizontal run. If your drain comes straight down from your tank, all of it will go to the sump. Tee’ing off that vertical pipe will be hard to get consistent flow to the fuge. One way to accomplish this is to put a valve on the main drain line to “backup” the drain to the fuge tee. Throttling the main drain is a risky proposition. You will need a small ball valve to the fuge to regulate a low flow. So the valve will not be open much. If something was to get in the valve and block flow, now you do not have enough total drain flow to drain your main tank. You run the risk of overflowing your display tank one day. The best bet it to tee off on a horizontal part, or at an elbow, or even incorporate a wye fitting so you can get flow to the fuge, and leave your main drain free flowing able to handle all the flow of the return pump.
For a sump, there is really no size requirement. Just big enough to hold your stuff. The bigger it is, the more volume it adds to your system.
As for the fuge, a common recommendation is 10X the system volume. So what ever your ACTUAL volume is, use 10%. It can be bigger, it can be smaller. But this is important to remember, the pods don't care. They just need a safe place to reproduce. As for any macro algae, bigger is not always better. Everything in the reef will only grow to the rate at which nutrients are provided. You could make a fuge 50g for a 90g tank and drop a basket ball size of Cheato in it, and you would probably watch it wither away.
Macro algae is not a solution to poor feeding and maintenance habits. Do everything you can to drop nitrates with proper live rock, maintenance and feeding habits, then use macro algae to sponge up the rest. In that scenario, the algae will only grow to what is there. My Cheato is healthy and is not dieing, however, it will only double it's size in 2 or 3 months. I had zero nitrates before the fuge, and I harvest very little Cheato.
There is some debate about this. Some want very little flow, some use a lot. Another common recommendation is 10X the fuge volume. So with 10 actual gallons in the fuge, turn that over 10 times per hour. That gives us a flow of 100 GPH. Now looking at 100 GPH, it looks like a trickle. It really isn't much
Others want a lot more than that. I have heard some running as high as 40X fuge volume. So that same 10g fuge would be 400 GPH. The reason is to "tumble" the Cheato. There are those that believe if you tumble a ball of Cheato, it will grow better. You basically drop the water in the fuge over a piece of glass or plastic. Something to redirect the flow over the top of the water. This hits the Cheato and tumbles it. You need a lot of flow for that.
Honestly, I think it sounds interesting. I have even wanted to try it. I just never had a reason. I don't really care how much Cheato I grow, just as long as my nitrates are zero, and I have no nuisance algae anywhere.
With very low flows, there will be Cyano growth. So some increase it to stop it. I don't really care as long as it is in the fuge. Others go even further and put power heads in the fuge for better flow. I see this as a bad idea. Remember, the pods need a safe place to grow to feed the coral. Throwing a blender in the fuge is counter productive.
There are many different ways to run a successful reef. There have been many filtration schemes long before I got into the hobby. I don’t want to suggest that those should be excluded, or that one way is the best way. What I will say is that it seems that the hobby has grown considerably, and the success of keeping very demanding species’ is in no small part to the progression of filtration. Today, the most common recipe for a successful reef tank is a high performance skimmer, lots of live rock, and a refugium. What that does not take care of, GAC and GFO can easily handle. I hope this helps.
Last edited by Powerman; 03-08-2011 at 10:10 PM.
|01-05-2010, 09:31 AM||#2|
great article Powerman K+
|01-05-2010, 09:41 AM||#3|
Excellent article -this should be made a sticky for folks to reference.
|01-05-2010, 09:44 AM||#4|
Thanks guys. I would love it if everyone posted pics of their sump or fuges so others can get a better look at some of the things talked about. I have a few more to post as well.
|01-05-2010, 09:47 AM||#5|
WOW, what a write up. Great job. What was the name of that bible? lol
|01-05-2010, 10:14 AM||#6|
Gread advice to any novice or pro alike! K+ to you
|01-05-2010, 12:55 PM||#7|
K+ awesome write up. PM sent.
|01-05-2010, 12:59 PM||#8|
Powerman, I just learned alot from your most informative thread on refugiums. Take a look at mine and tell me the best place for my skimmer. ASM G2 will arrive tomorrow, foot print is 11 X 10.
|01-05-2010, 01:06 PM||#9|
Thank you - perfect timing for me!! What a great write up. I'm going to print this off and use it!
|01-05-2010, 06:27 PM||#10|
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