extra filtration

[DI]

Does having extra filtration allow one to have more fish in the tank?
Can you ever have TOO much filtration? My tank is 55 gal. DI

[mistergreen]

nope. there are other things to consider when you add too many fish in a tank, not just filtration..

You have to think about stress levels from overcrowding, lack of oxygen, ease of disease transmission etc..

And the levels of nitrate will climb no matter how much filtration you have.

so, don't put too much fish in a tank.

[DI]

Point well made........Thanks, DI

[Martin Thoene]

Theoretically, increased filtration causing more water movement and higher oxygenation should allow a higher stocking density. The problem is if your power goes, suddenly you have no water movement and the fish will be very quickly compromised.

I believe that you cannot really have TOO MUCH filtration, but the actual flow produced may be excessive for certain types of fish. In most cases loaches will be perfectly happy with masses of water movement but other fish species may not. You have to strike a balance based on what species you keep.

Martin.

[crazy loaches]

Filtration is a very general term that could mean or include many things. Bio filtration? You could fill a 50 gallon drum with bio media and it would have very little difference with an appriopriate sized filter, since benefical bacteria will only grow at the rate there is food for them to consume. Mechinical filtration? Always good to filter the physical crud out of the water... but would 10 sponges in a row be too much? It would probably clog very fast and reduce flow. Does anyone run a diatom filter constantly? Not really, but every so often. Chemical filtration? Well depending on conditions, you might not need this at all. Then it comes to flow. There are so many aspects to 'filtration', and most of it is about finding a good balance.

Most good stocking suggestions would be based on the fact that one has appropriate filtration, along with a good waterchanging schedule.

It also depends on the fish, so each situation is unique. Some fish like more room (territorial & aggressive fish usually), some fish like loaches dont mind to pile on top of each other.

I freely admit that by most opinions my 75g tank is probably double the amount of stocking most feel comfortable with. But with two XP3's, a 1200gph powerhead, stuffed full of growing plants, O2 levels at saturation, and a weekly 50% water change, it seems to do just fine. Of course I dont intend to run it like that forever (since the fish - especially clowns - will grow much larger), I have a bigger tank there going in soon.

[mistergreen]

good points.

I think having a tank full of plants is better than having a lot of 'filtration'..

And I don't know if having a lot of filters running would increase O2... Wouldn't it just circulate O2 better but not really increase the rate of O2 exchange into the water? Maybe is you have large series of waterfalls.

[Diana]

Gas exchange happens at the surface of the air-water contact. At one extreme, still water, gas will diffuse slowly into the top inch or less of the water, and much more slowly diffuse into the rest of the water. This is why fish that lack for O2 will be found with their noses in the air, or at the very top of the tank.
At the other extreme, water that moves very fast across the surface of the tank may not have enough time to give up CO2 and accept O2. This water then goes deeper into the tank as the water circulates, but does not bring much O2 down there with it.
Somewhere in between is about right.
All the options for moving water have actually been tested, showing how much O2 is brought down into the rest of the body using different methods. I think lake and pond restoration was the driving force behind these tests. They found that something like a fountain pump that picks up water off the bottom and directs it upward worked the best. Centered in the pond was the best. Water that had some serious ripples was moving at the right rate. If it broke into whitecaps, or fountained up into the air this water was moving too fast. You would be spending more money on the power to move that water than the extra O2 accumulation was worth. (Again- pond or lake conditions- in an aquarium, some 'whitewater' might be the ultimate in oxygenation)

Basic concept: O2 enters the water from the air, and from plants. Keeping the plants thriving is a good way to get O2 into the tank for the fish and for the nitrifying bacteria. Water movement between 5x and 10x the tank volume per hour seems about right for many community fish. Directing that water across the top of the tank assures that the water is coming in contact with the air. Additional powerheads or pumps can be used to help clear dead spots, or to move more water across the surface.
For maximum effect look at a tumbling mountain stream- it is shallow, and the water does actually tumble, and bubble as it falls from one section to another. The bubbles themselves do little to add O2, but they indicate that the water is getting well mixed.

[chefkeith]

Each extra filter adds a layer of protection to the aquariums biological system. Filter redundancy has its rewards. The system will process Ammonia and Nitrite faster. But most importantly, if one filter stops working the overall water quality won’t suffer.

I use 3 canister filters per loach tank and I wouldn’t have it any other way. Just the other day, a filter had a kink in one of the hoses, which greatly restricted the water flow. It was probably like that for a few days. Had this been the only filter, the tank would have had ammonia problems.

[crazy loaches]

Yeah, redundancy is a good point I forgot to mention. Having more than one also allows you to clean one more thoroughly without worrying about effecting all its beneficial bacteria. Just clean them on opposite weeks/months whatever.

[mistergreen]

Diana,
Do you know of any studies on CO2 when it come to suface agitation?
Some say surface agitation release CO2, some say it helps in CO2 gas exchange...

I was going to do an experiment where i'd have 2 container of the same water except one would have an air pump... Then the next day or so, I would measure their PH & KH to find the CO2 in both containers.

[DI]

Many thanks to all of YOU!! This is such an amazing source of info....my 55 gal has a Whisper 330, an Emperor 280 & a Maxijet 1200. SO unless I hear otherwise, I will add a Rena XP2. By the way- the loaches seem to love the addition of the maxijet, your advice on that was great! DI

[chefkeith]

CO2 is denser than air. An aquarium with no agitation with a tight lid will have better CO2 exchange. I'll try to explain. When CO2 bubbles go to the surface, they don't go far. The CO2 blankets the water's surface because it is boxed in on all four sides, while being sandwiched between the water and air. That is nearly pure CO2 at the waters surface. Air contains only about 300 ppm of CO2.

On the other hand, this could be a bad situation for fish in planted tanks during the night, if the O2 levels get low. If fish go to the surface gasping for air, they will actually be breathing in CO2 instead, which will make their situation worse.

Surface agitation and hood vents near the top of the tank will lower those CO2 levels and increase the oxygen levels.

[mistergreen]

oh, I want high CO2 levels.

[chefkeith]

Here's a thought- If you have a tight fitting canopy hood and a powerhead with a venturi airline, run the the venturi airline from the powerhead to just above the waters surface. This way you'll make the most of the CO2 that lingers above the waters surface in the hood. I bet that would raise the CO2 and O2 levels in the water at the same time.

[DI]

I will place the venturi line as advised! thanks again, DI