I will try to address this point by point, as best I can...
See this is the question can you over filter, when you go into the subject in great depth it starts to get a little confusing, im like you i over filter i always have 2 externals running on all my aquariums, but is it actually needed??
"Need" is a challenging thing to answer, as different fish all have different needs. In theory, you need no more filtration than would be necessary to cycle sufficient water for
your bioload to keep ammonia and nitrite at zero. Where that threshold is would depend greatly on the type of fish you have, the volume of your tank, the amount of fish, the amount you feed, how often you water change and vac, etc. There are just too many variables to put a set number on it.
Can it cause more harm than good?
As pointed out, I believe the answer is simply, NO. As long as the fish are not struggling with the amount of current, I see no reason to purpose that it is possible that it could be "over-filtered" to a detriment. Most fish in the hobby come from rivers, and many of them actually prefer the faster currents. My glofish spend a good deal of time swimming in the current coming from my filters, I think that they think of it like an endless pool or treadmill of sorts.
The thing is surprisingly i think You will find that a lot of people have actually got immature filters and don't realise it.It does not matter how many filters you have in a system.
How exactly do you define "immature"? If you define it as unable to handle the full bioload of the tank by itself, then sure. But what does that matter? Most people who have multiple filters running do it, as far as I know to have a bit more circulation and/or a failsafe for a filter breaking. Of course, if a filter did break, there could be an ammonia spike, but not nearly as large as if there were no filter running afterwards. So, in my case, with only 1 filter working (since they are exactly the same filter I will assume for the sake of argument that they each can handle 50% of my bioload) if one broke down, my ammonia will go up only half as fast as if I didn't have that extra filter. PLUS, I will also mention that in cases like this, the established (I won't use the word mature, since it seems to be confusing) colony in the other filter could increase in size and actually take over the full job.
Filters work by mechanical, biological and chemical filtration. So therefore if you have say for instance 5 filters running on your tank, water is being mechanically filtered 5 more times than it would if you had one filter, however biologically (and this is the most important sort of filtration) you can only have as much biological filteration determined on the food provided,
Granted.
bacteria needs food to digest otherwise it dies, so if 1 spoonfull of bacterial food will feed one filter, and all you provide is one teaspoon of food, then it doesnt matter how many filters you have as you have only got enough food to feed one.
Also granted. But, there is also something to be said for "not putting all your eggs in one basket". Keeping the bacteria in multiple filters means that you are in less danger of catastrophe if one breaks down. I go away for multiple days consecutively every now and then. I don't leave anyone in charge of my tank. It runs fine on its own while I am away. And I know that
if one of the filters shuts down while I am away for any reason, I still have another filter working. I don't have to worry about it.
Extra filters are good for when you are over stocking/over feeding.
They will
help but the real key is water changes to keep the water quality high. Large water changes when overstocked are necessary, regardless of the number of filters you have running.
I think that people who have 2 sometimes 3 filters and do 50% 60% weekly water changes, are defeating the object as there is not enough food for these biological filter beds to be sustained.
This confuses me. How would a water change defeat the purpose? Assuming that the filters are fully cycled for the tank in question, the ammonia and nitrite remain at trace levels
at all times. Doing a water change removes the excess nitrAte, which the bacteria don't need/use. The ammonia will still be produced by the fish on a continual basis, so I don't get your point here at all. The water changes replenish minerals to the tank and remove nitrAtes and poo. Are you suggesting that leaving the poo in the tank is good because it produces more ammonia and allows a bigger bacteria colony? I will disagree with that. Removing the poo is the job of the keeper, not the job of the filter. The filters job is to keep it from fouling the water until such time as I remove it.
If you did parameter tests with all your (5)filters and then knock off 1 filter you would probably find that there is no difference.
Well, yeah, you can safely remove a full 1/3 of your biological media without worry of an ammonia spike, because the bacteria left behind will reproduce and fill in for the missing bacs. This is how many a keeper "clones" a filter to start up a new tank.
Dont forget the more efficeint the filter the more nitrate will be produced and you can only produce nitrate by the amount of organics that are in the water, so rather than extra filters an aenerobic nitrate filter would serve a much better purpose.
There are more nasties in the water and more reasons than just nitrate removal to do a water change. Granted it is a part of it, but IMHO, doing a water change has less to do with nitrates and more to do with overall clean water. Water changes keep the water quality of the tank high and allows the fish to deal with most pathogens that might come their way on their own. A filter directly designed to remove nitrates would mask the issue of needing to do water changes and could pose a problem long term.
I just want to see what peoples thoughts/answers are on how they filter etc..
Thanks for the replies guys.
You are welcome.
