Adding a Second Filter to Tank

[NikkO]

I haven't done research on this, but I think bio colonies in filters (with the exception of wet dry & bio wheels) is highly over rated...I'd bet that in most tanks 80-90% of the "bio colonies" are IN the tank, and not in the filter...

How can that big of a percentage be in the tank? It's like defeating the purpose of having a filter in the first place. It could be equivalent the filter, granted the plants, rocks and gravel have the same surface area as a filter. With smaller tanks I could see what you mean, but I'd expect 60, maybe 70% tops with those tanks if they had a lot of rocks, plants,etc.

 

[daveedka]

if you have one larger filter then you only need to clean one filter. If you have 2 smaller filters you need to clean 2.

Not sure how you derive that.
In the case of two filters half size as opposed to one large filter, the total media would be the same (assuming equal sizes) the inside surface areas would be the same (assuming equal sizes) the only real difference aside from the advantages would be the 30 seconds it takes to lift the extra filter off of the back of the tank. Now consider that it is typically (although not mathematically) easier to lift a smaller lighter filter twice than to lift a heavier larger filter once and the 30 seconds seems like time well invested.
cleaning two small filters should pose no more work than cleaning one large filter.
However in my case since I double up (or more) on large filters, I clean them half as often which equals exactly the same maintenance at the end of the year. As having one filter that I clean twice as often. So with that in mind when you consider the advantages, it makes sense to me.

I haven't done research on this, but I think bio colonies in filters (with the exception of wet dry & bio wheels) is highly over rated...I'd bet that in most tanks 80-90% of the "bio colonies" are IN the tank,

Biological filtration has three basic requirements (there are other vitally important requirements, but none that wouldn' be equal among the different components in the system)
1. food: ammonia, and nitrite respectively these are in the water column.
Bacteria doesn't have to catch it's food while it whizes by like a fish. Ammonia and nitrite are more or less locked into the water column equally everywhere, and the water that contacts the bacteria will deliver the food. remember bacteria thrive in high flow rate situations just as well. i.e. hydoponic tracks, rivers, sewers
2. surface area to cling to: if you compare the surface area of your substrate and decor to the surface area of filter floss, or filter sponges, you will find that unless you are using a very pourous substrate (most people don't) the filter media provides the greater surface area. this does not mean that bacteria doesn't estabilish in a tank, on virtually every surface, it only means that the largest potential colony is in the filter.
3. Oxygen: This is where the filter contains the great advantage. the o2 levels in a tank will always be lower as you go deeper, even with fabulous circulation, the gas exchange takes place at the surface and the lower levels have less O2. in some filters (hob's Particularly) there is a lot of turbulence which further increases o2 available for bacteria. In sealed filter, the increased water flow across the bigger surface areas, delivers o2 better due to the flow, and therefore the bacteria will thrive more readily in the filter.
The substrate in particular can only colonize bacteria based on O2 levels, and therefore that surface area which is the largest in the tank is hindered by O2 availability. Only with a UGF (or variation thereof) do you fully take advantage of the substrate surface area for biological filtration.

Finally, do filters really fail? I've had about 6 filters on 4 tanks in the past 7 years and have never had one fail....

cosidering your arguments against more than one filter, and the statement that none have failed, the math is a bit confusing
Either way filters can do and will fail, good quality filters do it less often, and more often a failure is a result of a bonehead move on the part of the fishkeeper. either way it can pose a danger.

7 years is by no means a short term test, but it isn't really a long term test either. I have four Hob's currently running, three of which have logged close to 10 years each without a problem. I don't trust them to live forever, and will not risk my fish to a mechanical item. There are folks aroung here wo log centuries worth of operation every few years. Many if not all of those people double up on filtration as well, for multiple reason. Many people use only one filter, and if done right it can and will work, but The advantages of doubling up are still there for those who want to do it. I also double up on heaters, and RFUG powerheads. redundancy reduces risk and increases peace of mind for me. When I couldn't afford more filters, I learned about UGF and RFUG which is still low cost, and still works well for me. But I never have and never will run them as a stand alone filter.
dave

 

[RTR]

Well, I have studied biofiltration capacities in my tanks quite a bit, and IME and in my unplanted tanks >>90% of the biofiltration is in my filters, mostly external bio-only canisters (some W/D, some FBF). But then, I never turn them off - especially not for extended periods.

Given time, the nitrification bacteria will be present in largest concentration in the areas providing 1) best oxygenation 2) best non-silting subtrate for attachment and 3) best water flow to provide nutients and remove waste products. Those three items are each and all maximized in my canisters. I can move the fish load and the canister together to a brand new setup and have no, repeat no, detectable unoxidized metabolites at all. If I were to restock the prior tank immediately, there would be major nitrification issues. Q.E.D.

In case of extended power outages, I do have proceedures for preserving the canister's funtionality.

Currently I do not have any unplanted RFUG operating, but they were the primary nitrification site when I did have such going and looked at this.

In my planted tanks nitrification in not an issue, as metabolic ammonia is taken up by the plants faster than the biofilters can oxidize it. Those tanks do have biofilters as well, but tests have shown them to be well seeded but immature in the sense of being incapable of processing the entire bioload by themselves, without the presence of the plants.

So I suppose that it all depends on the way your tanks are set and operated. I do know what mine do, but cannot say what the situation is in tanks operated by other techniques.

All of my above 10 gallons tanks are multi-filtered.

 

[geoffgarcia]

Plenty of great points made, my only counter point to all of the "surface area" issue is how can a person use a HOT filter that uses replaceable cartridges then? does that mean that there are 2 steps to these carbon filled cartridges
step 1 - upon replacement the carbon cleans the water
step 2 - the carbon becomes saturated but by this point enough bacteria has built up upon the pads that the carbon is not as necessary?
repeat
?

perhaps I've had success and not noticed differences based on filtering or not because I tend to not run my filters more than I run my filters? and I'm guessing that whichever approach you use (run it or dont) your tank will stabilize to, and if you switch u'll throw the tank out of flux and cause issues.
Also I use a fairly deep substrate (2-3") and have always kept plants and a fairly low fish load

Wow, well, I've had a whisper fail to restart after a power outage. I've failed to open shutoff valves on one canister. I've had two impellor covers to break during cleaning canisters. I've had a part fall in between canister baskets that caused the head to not seal correctly and the baskets to warp. I've overfilled baskets and caused a leak at the head gasket. I've used incorrect lubricant on gaskets and found they were stiffening and starting to fail. I've boiled the parts of an airdriven sponge filter and warped the uplift tube. I've cleaned an impellor and put it on the floor where it picked up a stray staple and then put it and the staple back into the unit and damaged the impellor assembly. Most of these things caused either leaks or parts replacement, but if simply putting the unit into a bucket wasn't enough to make it usable, then I had to take the filter out of service until it was repaired. So, that tank had to rely on the backup filter or I've had to improvise one quickly.

And I've managed to do all this in just 2 years of keeping fish, running 7 or 8 tanks at a maximum.

sheesh! u might want to buy a different brand of filter or let someone else clean them something ...thats just horrible

How can that big of a percentage be in the tank? It's like defeating the purpose of having a filter in the first place.

exactly my point

In the case of two filters half size as opposed to one large filter, the total media would be the same (assuming equal sizes) the inside surface areas would be the same (assuming equal sizes) the only real difference aside from the advantages would be the 30 seconds it takes to lift the extra filter off of the back of the tank. Now consider that it is typically (although not mathematically) easier to lift a smaller lighter filter twice than to lift a heavier larger filter once and the 30 seconds seems like time well invested.

many people dont use simple HOT filters, for a canister opening and doing maintenance including cleaning the internal parts is much more involved and can easily take 10-20 minutes if ur diligent about it. to do 2 of them (regardless of their size) would take exactly twice as long.

cosidering your arguments against more than one filter, and the statement that none have failed, the math is a bit confusing

I've upgraded - not failed nor run doubles.

 

[daveedka]

many people dont use simple HOT filters, for a canister opening and doing maintenance including cleaning the internal parts is much more involved and can easily take 10-20 minutes if ur diligent about it. to do 2 of them (regardless of their size) would take exactly twice as long.

I still don't understand how cleaning half as much will take the same amount of time. It takes a good 30 minutes to properly tear down and clean my Emporer, and at least 15 minutes for the Ac's despite their simplicity. I still only have to do it half as often when I run two filters. so If I run one I have to invest 30 minutes every 2-3 months for deep cleaning, and if I run two I have to invest 30 minutes every 2-3 months for deep cleaning. Somehow that still seems equal to me. if it was cannisters, that take 20 minutes as you suggest, then I would invest 20 minutes every 2-3 months with one, and if I had two of them I would invest 20 minutes every 2-3 months as well. I can't find the difference there either

If I use a filter of half the size, there is still half as much of it to clean whether it's a cannister or HOT it would still be far closer to the same amount of time than it would be to twice the time.

Plenty of great points made, my only counter point to all of the "surface area" issue is how can a person use a HOT filter that uses replaceable cartridges then?

you'll find that most of us who are serious about filtration, don't use replaceable cartidges. They are expensive, and every time you replace them you risk a mini-cycle. The Carbon is largely unnecessary, except in abnormal cases such as medication removal or tannin removal (both short term uses) and floss, sponges are much less expensive than throw away cartidges. I use sponge because I can throw it in the maytag and don't have to wash it out by hand. I also use alternative bio-filtration techniques so I am not dependant on my sponges being my primary bio-filter which would be the case if I had only one filter on the tank. Marineland, designed the bio-wheel set-up based largely on the danger of mini-cycles when replacing cartridges. The idea being that the wheels are the primary bio-filter, and the cartidges are not. The srface area of a bio-wheel is truly immense, and the wet-dry effect is obviously very good. Almost any decent filter manufacturer will caution against changing all of the media at once for the same reason.
dave

 

[geoffgarcia]

you'll find that most of us who are serious about filtration, don't use replaceable cartidges

I'm aware of that, but I'm wondering how the industry allows them if they are so pointless

 

[geoffgarcia]

I still don't understand how cleaning half as much will take the same amount of time. It takes a good 30 minutes to properly tear down and clean my Emporer, and at least 15 minutes for the Ac's despite their simplicity. I still only have to do it half as often when I run two filters. so If I run one I have to invest 30 minutes every 2-3 months for deep cleaning, and if I run two I have to invest 30 minutes every 2-3 months for deep cleaning. Somehow that still seems equal to me. if it was cannisters, that take 20 minutes as you suggest, then I would invest 20 minutes every 2-3 months with one, and if I had two of them I would invest 20 minutes every 2-3 months as well. I can't find the difference there either

dave I'm not sure what assumptions your making but mine are this:
1) we are comparing 2 scenarios, each having equal total capacity
scenario a) two smaller filters of X capacity (total capacity = 2x)
scenario b) one larger filter of 2X capacity (total capacity = 2x)
2) both a and b will become "full" and need cleaning in exactly the same amount of time.
3) once they become "full" each filter will require 20 minutes to clean
4) the cleaning time of a (2 filters) will be exactly double that of b despite the fact that each smaller filter has half the waste material in it. Its not a matter of how much waste needs to be cleaned, rather a matter of removing/unplugging/cleaning propellers/etc....therefore:
scenario a) two filters of X capacity will take 20 minutes EACH to clean ever 2-3 months, for a combined cleaning job of 40 minutes
scenario b) one filter of 2x capacity will take 20 minutes to clean every 2-3 months

 

[geoffgarcia]

If I use a filter of half the size, there is still half as much of it to clean whether it's a cannister or HOT it would still be far closer to the same amount of time than it would be to twice the time.

this is where we diverge.

ANY filter cleaning should take roughly the same amount of time regardless of the size fo the filter...

cleaning a larger filter doesn't take any longer than cleaning a smaller one, they still just use 1 impellar, have one set of input/output tubers, have one main chamber, although they might have double the media storage, cleaning media is usually the fastest part of my cleaning process....

 

[daveedka]

cleaning a larger filter doesn't take any longer than cleaning a smaller one, they still just use 1 impellar, have one set of input/output tubers, have one main chamber, although they might have double the media storage, cleaning media is usually the fastest part of my cleaning process....

I don't at all find this to be the case, to tear down and clean my Emp 400 properly takes significantly more time than to tear down and clean my penguin 125. not to mention that is is much harder to remove, and dissasemble the big filter than the little one. I do not currently have a 280 to make a more accurate comparison on what half of a 400 would be like. but would easily say that I can clean the 125 properly in less than 10 minutes while the emporer with so much more internal surface to clean takes a good solid 30 minutes. I can clean my powerhead impellers in about 30 seconds, but the emporer impellar (larger) takes a good bit of brushing and rinsing to be equally as clean. The Ac's really aren't a great one to use for an example, solely based on the fact that it takes no time to clean an AC of any size, They are a platic box with a removeable impellar and motor. it takes far longer to get them off the tank than to clean them. but once again, the 500 is far more difficult to work with than the 300 or the little guys. so it takes longer (probably twice as long) to clean it and have it running again. I like you mentioned don't give the media much thought as it goes into the maytag and new gets put in when I clean. The media is a weekly/ bi-weekly thing for me with all filters as a rule. deep cleaning only happens about every 4-6 months on each filter.
dave
Dave

 

[amosf]

I tend to agree and disgree with both dave and geoff, but then everybody's situation is different. I find that each filter takes a certain amount of time to clean so two filters takes twice and long as one filter. But that's not really a big deal. I tend to also only use one filter per tank, but then I'm around the tanks a lot so if a filter fails I'll know about it in a couple of hours and have replacements I can use. It already takes enough time to clean 4 tank filters, so if there was two or more per tank it would be more work IMO and to me larger filters are easier to clean - but then I use home made wet/dry.

And as for where the bacteria are. They are everywhere of course. With my 50g the gravel is very open and coarse so a lot of bacteria will be in the gravel... But then I have a wet/dry filter with good water flow and plenty of O2 and a very large surface area with very low silting potential, so I can be confident that the greater majority of bacteria are in the filter.

Switching these sorts of filters off for extended periods of time would IMO be a 'bad idea' and severely reduce the nitrifying capability of the tank. Due to the gravel situation it might survive okay and the bacteria would recover fairly quickly, but I would expect a spike.

So IMO having two filters is not a bad idea if you don't mind a little more time cleaning, but at the same time I don't think having one good filter is a bad idea either provided you are not away from the tank for extended periods of time.