View Full Version : Filtering a 350

05-05-2003, 03:54 PM
I was at a LFS today talking to the owner. He has a 320 gallon packed full of africans Large Fronts and all.

I asked him how he filters it as it looked like just 3 ac 500 a couple powerheads and a large sand bed filter. Believe it or not that was it and the tank was crystal clear. I thought you would need a sump on a tank that size? He says not on freshwater. What does everyone think?

I read CHC post in the Equipment and water chemistry http://www.cichlidforums.com/showthread.php?s=&threadid=1882&perpage=15&pagenumber=1 and the sand filter makes sense as far as the biological part. I guess I just worry about the mechanical filtration on a tank this size.

I ask as I am currently looking for a 350 and have always been under the impression I would need a sump.

05-05-2003, 04:17 PM
IMHO, a sump would be the cheapest and best way to go. If you are worried about mechanical filtration, 3 ac500 will definetly not do the job. For a 350 gallon tank, i would use a fluidized sand filter of considerable size and about a 30 gallon sump with a 1.5-2 foot tall bio tower (5-7 gallons of bio media) You can use an overflow and several layers of micron padding before the bio tower (that should take care of mechanical filtration). If you are extra worried about it, you could get some powerheads and use prefilters on them, i find they work well for tank circulation and filtration. :D

05-06-2003, 06:33 AM
Rudy, I didn't mean to imply on that other post that you need separate filters (one for mechanical and one for biological). As you know, both processes take place in most currently available units today. Some are better at one or the other though, so I do suggest supplemental filtration at times.

With respect to the 350 filtration, I agree that the 3 AC's, etc. is much too little and far too ineffecient for such a large system (unless by sand bed filter the shop owner meant he has a rapid sand canister, the huge things they filter pools and spas with). You really need to be moving a great deal of water each hour in this system (at least 2,000 gallons IME). Keep in mind the possibility of dead spots, etc. in a tank this size.

The best way to move water in a large tank is an overflow design. In such a tank, there is no need to mechanically pump water from the tank..... only back into it. However, if you purchase a standard aquarium with built in overflows you will never get the flow you need since most stock tanks have 1" or maybe 1 1/2" overflow drains, far smaller than is necessary to move the kind of water you need to. By the time you factor in twists and turns (i.e. PVC elbows, etc.) you're really only getting 700-800 gallons of flow. It makes no sense to me how aquarium manufacturers use the same size plumbing regardless of tank size (and it's no wonder reef keepers have such little success with that inherent flaw built in to their systems). I mean, the two overflows on an Oceanic 90 gallon are the same two you'll see on an Oceanic 220 gallon...... so you're moving no more water to the sump in the bigger tank. I will never buy a big tank from a stock manufacturer again!..... unless, of course, they change their designs. The overflows on my 300 are 2" pipes and there are six of them. Also, rather than having just six holes in the back of the tank, the entire available length of the tank is perforated so that nearly the entire surface area of the tank is skimmed into a box adhered to the back outside of the tank (the 2" pipes are the drains there). Most of the organic waste in a tank is on the very top surface film so I am sure to utilize the absolutely dirtiest portion of the water as a supply to the filter by skimming just a thin layer.

Once you have flow, it is fairly easy to filter it. If you construct a sump with a wet/dry filter design it can also be much cheaper than other methods (multiple canisters, etc. would have to be utilized otherwise) as your only big costs are the sump and the return pump. The bigger the sump the better as it would allow the most flexibility and largest bio-area. I try to get my sumps about 1/3rd. the size of the main system. Keep in mind the sump is rarely more than 1/4 full, and you also need room for the water to back flow into it in the event of a power failure (that is, the water will back-siphon until it drops below the level of the return pipes; you can put in check valves or anti-siphon air holes, but I prefer foolproof methods!).

I like to be able to remove each days particulate waste rather than let it sit for a couple of weeks in the filter, so running the water first into a micron bag works well for that. You'll actually get the clearest water you've ever seen with the micron bag approach. The water can then trickle over a bio-tower and then flow into a holding area where you can place heaters, etc. Then it is just pumped back into the tank. So, the first two types of filtration are accomplished easily (mechanical in the micron bag and biological in the bio-tower). If you need the third type, chemical, all you need to do is drop in bags of resins, etc. into the sump and you're set.

Returning the water is easy with a big pump, and I like to make something of a manifold over the tank (kind of a PVC loop) with return nozzles located in various places along the pipe run. The water is thus reutrned at many different points above the water surface (actually the reurns are just barely submerged) to better distribute the return flow and eliminate the need for anything visible (i.e. powerheads) in the tank. I try to get a big circular flow: down from the top front across the bttom and back up to the top back where the overflow screen is. Remember, however far you submerge the returns is how much water will back-siphon into the sump during a power outage (about 10 gallons for each inch of water in a standard 30" high 300 gallon).

Once you're all set up, you'll be getting thousands of gallons of flow through your tank, all micron filtered and all trickled over a huge section of bio-media. You'll see no visible equipment, and the costs (relatively speaking) would be modest. Just figure how many canisters or power filters you'd need to approach that, and even if you could make it work you wouldn't get the quality of filtration drop per drop. The big thing, though, would be serving all those filters. That could really get expensive; it would at least be a major hassle. With a micron bag, all you do is dump it out and replace it (bleaching it clean every few times; have an extra on hand).

So, a sump based system while sounding more complicated is actually the simpler AND more efficient approach

By the way, I'd stay away from a fluidized bed as anything other than supplemental filtration. FB's utilize a great deal of oxygen in their processes, and if the water flow is stopped for any reason (power outage, equipment servicing) the bio-flora in the bed die within just a few minutes. That's not a position to be in! Most big aquaculture industries that use FB's have backup generators, etc. to keep that from happening. I've messed around with battery backups, etc. but it's not worth all the trouble when a bio-tower of bio-balls is much less prone to biological collapse (but it can still happen).

It may make you more certain of the best approach to know that I have a friend who runs a Marine Science Museum. When you go look at her filtration (and she's supposed to be the expert, right?), she uses overflows attached to wet/dry filters on all of the small tanks (small to her is anything less than a few thousand gallons!). Of course, things do get a bit more complicated on the big 50,000 gallon displays, but you'd be shocked how simple it really is when you get an up close look.

05-06-2003, 09:04 AM
First of all Surfdude and CHC I want to thank you for your reply on this. Surfdude you are right on that one. Pumps are pretty expensive here however it would be cheaper in the long run. It wpould be just less time consuming to do it the other way. CHC your post more than answers my question and has my brain ticking like you would not believe.

I understand that the biological and mechanical filtration occurs usually in the same filtration unit. My thinking was that in this case I would more or less seperate them to run more in one than the other. I guess my thinking was that the biological filtration would be the sand bed filter for the most part as the acs in my opinion would not help a heck of a lot other than water flow and mechanical filtration. I do remember you stating the problem with a sand bed filter as primary filtration. Something as simple as the powerhead quiting, or the prefilter falling off or whatever I am screwed as the ac's would not be able to handle it. So I was trying to cheap out and obviously that will not work.

Having said that your sump idea fascinates me. I have been reading on King Vinnies etc on building sumps however most of them refer to a reef system sump.

You are right about the drainage as I have never really thought about it but the overflows are the same size. I guess for the most part to be pretty much generic for the market place but it does not work with every situation.

Do you think you could take some pics of your system, or direct me to where I could find something like it as I am now thinking custom is the way to go. I will build the sump. I am pretty much picturing what you are describing, however the actual sump and situation of it is un clear.

05-06-2003, 10:46 AM
If you PM me with a fax number I could send you a layout. I designed it and had a friend build it for me. He's the same guy who built the tank.

I am going to buy a digital camera so I can post pix. I'll make sure to post it here.

05-06-2003, 10:51 AM
Check your pm.

05-06-2003, 03:17 PM
Fantastic discussion. Chc, how is you overflow designed? I have seen a lot of plans for overflow boxes, and a major complaint with them is the constant sucking noise. Is this a problem with your design?

Also, at what size would using a sump be better than using HOB filters. Ideally, I would prefer a sump on any tank, as it allows me to remove the heater and other visible equipment from the tank. Would it be beneficial and effective to use a sump on a 135, or should it be reserved for tanks over 200 gallon, etc?

05-06-2003, 03:32 PM
I went and talked to a guy in Calgary here who builds aquariums Aqua Enterprises. (if anybody has heard of them I would love to hear from you) They build sump systems packages. Tank and sump and all for anything over 90 gallon. This is for the vary reason that Chet said. They do commercial work and so clients do not like intake hoses. There packages are standard at 1/3 the tank size which is exactly what Chc said. The overflows however were 1.5 inches and only 2 a tank all the way up. They can change this to whatever you want though.

They were kind of pricey, but may be an idea for just the tank anyway.

05-08-2003, 09:04 AM
Chet, I think a sump would be beneficial regardless of tank size, it's just that filtration issues (e..g. getting enough flow, a big enough bio-chamber, etc.) don't start to become headaches in fresh water until you reach 100 gallons or so.

If I had it my way, I'd have a sump on any tank 40 gallons or more. It's just much more efficient, it adds to the total volume of the system, it looks better, it's easier to service, etc. When using smallish tanks (40 gallons for instance), you can hook up several tanks to the same sump, so that DRAMATICALLY reduces maintenance, costs, water quality issues, etc.

Rudy, does that manufacturer use glass or acrylic?

By the way, you've both got private messages....

05-08-2003, 09:10 AM
Rudy, does that manufacturer use glass or acrylic?

Only glass unfortunately. There is not a heck of a lot of acrylic tanks around here. If you go out west into B.C. they seem to be around but not here. In all honesty I have never actually seen someone with an acrylic tank in Calgary.

05-08-2003, 03:55 PM
I actually prefer glass. It's less expensive, much more durable, and you get to access the entire surface area (acrylic has those support beams). Of course, glass is MUCH heavier.

If you get a big tank, make sure the bottom sits flat on the stand (not a floating bottom like you get with AGA, Oceanic, etc.).

05-08-2003, 06:36 PM
Originally posted by chc
I actually prefer glass. It's less expensive, much more durable, and you get to access the entire surface area (acrylic has those support beams). Of course, glass is MUCH heavier.

If you get a big tank, make sure the bottom sits flat on the stand (not a floating bottom like you get with AGA, Oceanic, etc.).

does the tank have to be custom-made in order to get the flat bottom feature?

05-09-2003, 08:45 AM
Chet, sorry I didn't see the question about the overflow design. To eliminate the sucking noise most people use a Durso Standpipe (or a twist on that same idea). Just plug those two words into a search engine and you'll get several pages.

Mermaid, yes. I think you will need to special order it that way, but most custom manufacturers will probably make them that way regardless for any tank of good size (200+).

Also, I actually would use acrylic if I were sure I knew what was going to be in the tank forever. Most of the scratching seems to occur when people move things around. Also, I am concerned about yellowing of the acrylic, but I hear that isn't as much of a problem as it used to be. At least at first, acrylic is optically better.