Canister filter get really dirty if you don't clean them in a while. - Page 2 - The Planted Tank Forum
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post #16 of 23 (permalink) Old 07-17-2016, 07:12 PM
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I completely agree, Nordic.

I don't have canister filters as I can't stand them, so I use HOB's. I used to clean them out monthly while rinsing filter pads with every water change, but since I had that one outbreak with ich a couple of weeks ago, squeezing out sponges along with pads is a weekly thing now. The ich issue has come and gone, but it seems to have deepened my OCD when it comes to tank cleaning along with gear such as siphons, ect...

Yesterday was tank maintenance day. I did my usual thing but found that for the 2 tanks that have 2 filters, only one side really collected any crud while the other side was fairly clean. It was a odd, but everything got rinsed anyway.

I equate dirty filters to sitting the tub in one's own filth. No offense to those that enjoy a bath.
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post #17 of 23 (permalink) Old 07-17-2016, 08:46 PM
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When the filter material becomes filled and more clogged, the aerobic bacteria have less oxygenated water flow to break down ammonia and nitrite into nitrate, which plants use, but nitrate can build up in the aquarium if water changes are not performed. However, as aerobic bacteria dies off in the absence of oxygen due to the reduced flow, it is replaced by anaerobic bacteria, which further breaks down nitrate and other wastes into free nitrogen (which mostly leaves the aquarium as a gas) and into other nutrients that plants can use, so anaerobic bacteria isn't all bad. But another product of anaerobic bacteria is hydrogen sulfide (you know, that "rotten egg" or sewage smell?) and other toxins, which was the cause of "sudden tank-death syndrome" way back in the early days of aquarium keeping, before UG filters, power filters, and before affordable artificial lighting was sufficient for growing many plants. (Basically what was happening was a substrate--usually fine gravel or sand--was too deep and went undisturbed for a long period, and then something dug a little too deep and hit a pocket of anaerobic bacteria, releasing the hydrogen sulfide and killing everything in the aquarium.)

That said, in his book, "Encyclopedia of Aquarium Plants", Peter Hiscock recommends allowing part of the filter medium to become partly anaerobic by alternating the rinsing of half the medium and leaving the other half " dirty" and somewhat clogged, and rinsing that half the next time the filter is cleaned, leaving the other half unrinsed. This is said to naturally provide nutrients for the aquarium plants. Whether you prescribe to this train of thought or not probably depends on your personal degree of anal-retentiveness, but I imagine a small degree of anaerobic activity in a filter that is regularly cleaned may be beneficial to plants, but wouldn't do a thing for animals, other than potentially harm them. Besides that, most hobbyists here are artificially providing nutrients by dosing in controlled measure, although if you wanted to achieve a balanced, fully closed "natural" aquarium system without any additions other than light and topping off the water level, it might have merit.

As has been stated above, it all depends upon many variables, including your intentions for the aquarium, the animal stocking load, the plant stocking, how much you feed the animals, what scavengers you have, etc.

I just bought a setup that included two Fluval 305s, which I immediately put on a 55 without cleaning. (The 55 is newly set up, specifically for three plecos that came with the new setup, so I wasn't concerned about introducing anything harmful to an established aquarium, plus I wanted the ready-made nitrogen cycle for the plecos.) When I noticed the flow was practically nil, I broke one down to see what the problem was. The filter pads were so clogged and full of what can only be described as "mud" that a filter basket filled with filter pads in the bottom and ceramic bio-medium on top of that actually floated in the bucket for several minutes, until I got impatient and pushed it under. Now THAT'S a dirty filter!

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post #18 of 23 (permalink) Old 07-17-2016, 11:18 PM
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Unclean filters are nitrate factories. This is a problem in any saltwater setup, that's why they don't use canisters. It's a problem in a fish only freshwater, need to clean the filter, often. Doesn't matter in a heavily planted tank, monitor your NPK levels and dose accordingly with your unclean filter supplementing. Clean canister when flow drops to a level you don't like. I clean mine once a year just for the heck of it....the only thing in my filters is ceramic bio media.
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post #19 of 23 (permalink) Old 07-17-2016, 11:21 PM
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Originally Posted by Olskule View Post
...I imagine a small degree of anaerobic activity in a filter ... wouldn't do a thing for animals, other than potentially harm them.

Good point @Olskule . The whole NO3 reducing conditions is again aimed for fish-only setups. It will remove bioavailable N from the system thus will not provide nutrients for plants, naturally or otherwise. As you rightly say, bacteria that grows in anaerobic conditions will create all sorts of nasty bi-products, most of them poisonous to higher life forms H2S, CH4...The nice NO3 will be converted back to the very lethal NO2 in the process towards N2 gas, not sure I want that being pushed by the canister in the aquarium. It will also make some metals back into bioavailable/reactive form... such as Fe but also Cu, Pb. I hope you see by now why anaerboic bacteria have no place in the filter ( in addition to what I mentioned in the previous post).

The only time I have seen anaerobic areas in the filter was when it was powered off for more than 3 days. Unless the canister filter has a very quick bypass or is designed to have no flow areas, it would be very hard to create anaerobic conditions when new oxygenated water flows by.

That being said, I have nothing against anaerobic areas. Their place is in the substrate and in limited amount.

The more we understand natural ecosystem, the more we realize our aquariums are far from natural. The faster we realize that we cannot create a natural ecosystem in our glass box, the better we become at keeping plants and fish alive and well.

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post #20 of 23 (permalink) Old 07-18-2016, 12:48 AM
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Originally Posted by Maryland Guppy View Post
When the waving of the plants slows down a bit I'm in the canister.
This is me. When I first started my 29, I cleaned the filter every other week. Now it's more like every three months. As the tank has matured, it definitely throws off less detritus. OTOH, on the 125, which is about two months old, I change the floss pretty much every night, and the socks the floss sits in at least weekly.
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post #21 of 23 (permalink) Old 07-18-2016, 12:49 AM
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It is nearly impossible to culture anaerobic bacteria in a freshwater aquarium filter with any flow through it. There's just too much O2. You could in a filter that gets turned off and just sits for days. But lets not assume that all anaerobic bacteria is the kind that will convert nitrates into nitrogen gas. Moreover are the decomposition types that make good water putrid.
Also lets be clear - it is aerobic decomposition bacteria (not anaerobic and different than the beneficial bacteria in the N2 cycle) that typically decomposes detritus, food and plant waste in the filter and the substrate into plant usable nutrients. You would typically only find anaerobic bacteria in deep sand or under decor like rocks where oxygenated water does not flow....and then only if there is an ample food source.
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post #22 of 23 (permalink) Old 07-19-2016, 07:46 AM
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In ideal circumstances it's very different to a car oil filter.
The job of a car oil filter is to trap bits of suspended solid material so that they don't damage the engine, eventually the filter fills up with that solid material so you have to change it.
The primary job of a canister filter is to convert dissolved ammonia in to dissolved nitrate. The nitrate isn't removed from the system by the filter, that's done either by plants or by water changes. Therefore nothing is building up in the filter, so nothing needs changing ever.

That's the ideal situation and it only accounts for the primary job of the canister filter. A secondary job is removing suspended solids so your mechanical layer will need changing eventually. Also, Nitrosomonas and Nitrobacter aren't the only things living in your filter, there is other stuff growing there which is less desirable so that needs removing eventually.

All that theory doesn't actually tell you when you should clean your filter. But it does give me a chance to check if I understand filters correctly (please tell me if I'm wrong). Personally I'm going to go for every month or when I see less waving of the plants as that seems to be the consensus.
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post #23 of 23 (permalink) Old 09-13-2016, 09:56 AM
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Originally Posted by TwoTurtles View Post
The primary job of a canister filter is to convert dissolved ammonia in to dissolved nitrate. The nitrate isn't removed from the system by the filter, that's done either by plants or by water changes. Therefore nothing is building up in the filter, so nothing needs changing ever.
I challenge anybody with a canister filter to test the disgusting water that they accumulate to see of this is true or not. The answer is not, but since you feel as though there is no way filters can hold on to said gunk, test it for yourself. All the fish food, fish poop, dead leaves and whatever else that goes into the filter that sits around brewing like a foul-smelling stew does not simply go away because a person has a planted tank. Filter pads and sponges need to be rinsed, bio media can become overloaded with crap so it no longer functions properly, ect...
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