What causes a tank to recycle

Kassh4815

I am new to the aquarium keeping world and I have had my tank for roughly 2 months little longer. I am one of many that listened to LPS and ended up doing a fish in cycle and want to avoid that at all cost.

So I would like to ask what causes a tank to recycle and how can I avoid it? It’s time to change the media in my HOB filter and I’ve read to keep the old media in there to help populate new media with beneficial bacteria but I get conflicting answers on that and how long. Thanks for advice ahead of time!
 

Dunk2

I am new to the aquarium keeping world and I have had my tank for roughly 2 months little longer. I am one of many that listened to LPS and ended up doing a fish in cycle and want to avoid that at all cost.

So I would like to ask what causes a tank to recycle and how can I avoid it? It’s time to change the media in my HOB filter and I’ve read to keep the old media in there to help populate new media with beneficial bacteria but I get conflicting answers on that and how long. Thanks for advice ahead of time!
Changing or replacing filter media is a common reason. Essentially, you’re throwing out a majority of the beneficial bacteria that consume ammonia and nitrites.

What type of media are you referring to and why do you think it needs replaced after 2 months?

Unless the media is literally falling apart, it shouldn’t be replaced. When it gets gunked up, swish it around in tank water you remove during a water change.
 

Kassh4815

HOB top fin that came with the aquarium 36 gallon bow front. Currently I have had the media in for 2 months and a water polisher for 2-3 weeks and it’s lookin a bit….. gross. I don’t use the “replace now” float piece that’s on the filter that thing was red after 2 weeks. Figured it was time?
Changing or replacing filter media is a common reason. Essentially, you’re throwing out a majority of the beneficial bacteria that consume ammonia and nitrites.

What type of media are you referring to and why do you think it needs replaced after 2 months?

Unless the media is literally falling apart, it shouldn’t be replaced. When it gets gunked up, swish it around in tank water you remove during a water change.
Ment to reply directly sorry.
 

Dunk2

HOB top fin that came with the aquarium 36 gallon bow front. Currently I have had the media in for 2 months and a water polisher for 2-3 weeks and it’s lookin a bit….. gross. I don’t use the “replace now” float piece that’s on the filter that thing was red after 2 weeks. Figured it was time?
The “replace now” float accomplishes a couple things. . . It allows Top Fin (and other manufacturers) to sell more filter media (cartridges?). And it causes quite a few new fish keepers to lose their cycle.

Filter media should look a bit gross. As I suggested above, swish it around in water removed from your tank during a water change. I do that with the media in my HOBs every 4 weeks or so.
 

Kassh4815

The “replace now” float accomplishes a couple things. . . It allows Top Fin (and other manufacturers) to sell more filter media (cartridges?). And it causes quite a few new fish keepers to lose their cycle.

Filter media should look a bit gross. As I suggested above, swish it around in water removed from your tank during a water change. I do that with the media in my HOBs every 4 weeks or so.
so when should I replace the cartilage. I’m fine with never but I assume at some point it has to go.
Never mind you covered that too. Sorry missed the bottom of your message
 

Azedenkae

I am new to the aquarium keeping world and I have had my tank for roughly 2 months little longer. I am one of many that listened to LPS and ended up doing a fish in cycle and want to avoid that at all cost.

So I would like to ask what causes a tank to recycle and how can I avoid it? It’s time to change the media in my HOB filter and I’ve read to keep the old media in there to help populate new media with beneficial bacteria but I get conflicting answers on that and how long. Thanks for advice ahead of time!
If the beneficial bacteria dies off, then a tank would re-cycle. This is a rare occurrence though.

Often what a lot of aquarists perceive as a tank re-cycling or crashing is rather that from the start the tank was never properly cycled in the first place.

For example, some aquarists would just dose some ammonia into a tank or add in a bunch of fish food and call it a day when both ammonia and nitrite read zero. This does indicate some nitrifiers have grown, but may not necessarily be to the extent to which can handle stocking. Hence once it gets to the actual introduction of fish, ammonia rises and suddenly it seemed like things crashed. No, there was just never enough nitrification capacity to handle the stocking in the first place.
 

Kassh4815

If the beneficial bacteria dies off, then a tank would re-cycle. This is a rare occurrence though.

Often what a lot of aquarists perceive as a tank re-cycling or crashing is rather that from the start the tank was never properly cycled in the first place.

For example, some aquarists would just dose some ammonia into a tank or add in a bunch of fish food and call it a day when both ammonia and nitrite read zero. This does indicate some nitrifiers have grown, but may not necessarily be to the extent to which can handle stocking. Hence once it gets to the actual introduction of fish, ammonia rises and suddenly it seemed like things crashed. No, there was just never enough nitrification capacity to handle the stocking in the first place.
Ya I ended up doing a fish in cycle because I didn’t do my own home work and trusted my LPS.so I went through the painstaking 2 months of treating and water changes every day or other day to keep things as safe as I could. I just do t want to do it again.
 

Azedenkae

Ya I ended up doing a fish in cycle because I didn’t do my own home work and trusted my LPS.so I went through the painstaking 2 months of treating and water changes every day or other day to keep things as safe as I could. I just do t want to do it again.
Mm, definitely gotcha.

My recommendation is to keep the current biomedia and just leave it be. No reason to break something that does not need to be 'fixed'. The only thing I may recommend is adding more, better biomedia if you have the chance and it fits in your current filter. Something like Seachem Matrix or MarinePure would be best. MarinePure comes in little 'gems' that works well to fill up most filters.

Unfortunately with fish-in cycling there's not much you can do with absolute certainty to ensure you don't see at least minor spikes in ammonia and/or nitrite each time you add a new fish. The exception is of course the nitrification capacity of your tank already exceeds what is needed to handle your current stock and can readily handle more as is, but that... relies on a lot of different factors.

My suggestion is to just add fish slowly and monitor levels each time, dosing Prime and similar products and doing water changes as necessary.
 

RayClem

I have been keeping fish for over 60 years. If done carefully, there is nothing wrong with a fish-in cycle. However, I always run the tank empty for two weeks before adding the first fish. I "feed" my empty tank with fish food to add a source of ammonia to get the cycle started. If I have filter media from another tank (gravel, filter floss, carbon, etc.), I will add that to provide a source of beneficial bacteria.

After a couple of weeks, the bacteria that convert ammonia to nitrite should have begun to develop, but there will be little of no bacteria to convert nitrite to nitrates for a few more weeks.

After two weeks, I will add a few hardy fish such as platys that can tolerate less that perfect water quality. They will be the only inhabitants of the aquarium for the next month while the cycle is developing.

Many hang on back filters contain replaceable cartridges that contain a thin layer or two of filter floss and a small amount of activated carbon. They are very convenient to use as they are designed to be disposed. They provide a constant source of income for the filter manufacturer....good for them...not so good for you or your fish.


Many experienced fishkeepers have removed activated carbon from their filters. Although there are times when activated carbon is quite useful, carbon does its job too well. It removes things beneficial to your tank as well as things that are bad. Furthermore, since carbon is black, there is no way to telling when the carbon has done its job and needs to be changed.

You can purchase filter pads and cut them to size to fit your filter. These pads are several times thicker than the floss on your filter cartridges, so they do a much better job. When you do your water changes, remove the pads and gently squeeze them out in the old aquarium water to remove the excess debris. The beneficial bacteria are attached to the fibers of the pad, so most will remain. Over time, the pads will deteriorate to the point they will no longer hold their shape and need to be replaced. However, that will be a lot less frequent than the cartridges.

If possible, have two filters in your aquarium. that way, you can do maintenance on only one of the filters at a time. I have some tank with two HOB filters. I have a tank with a HOB filter and an internal sponge filter. I have a tank with a HOB filter and a canister filter. They type of filters you use is up to you. By having two filters, the second filter will keep your biological filter going strong, even if you have to replace the media in the other filter.

Some brands of hang on back filters such as Aquaclear, Seachem Tidal, and Fulval "C-series" come with filter sponges and other types of filter media rather than replaceable cartridges. Overall, filters such as these will do a superior job of maintaining your aquarium. However, if you notice, cartridge type filters generally have lots of empty space. If you load up that empty space with filter media, your will improve the efficiency of the filter.
 

Kassh4815

I planned on adding a 2nd filter when the time was right but I should probably get it going now so I can make sure it has the beneficial bacteria needed
 

Dunk2

I planned on adding a 2nd filter when the time was right but I should probably get it going now so I can make sure it has the beneficial bacteria needed
It’s never too soon and you can never have too much filtration, so long as the water flow isn’t blowing your fish around the tank.
 

leftswerve

If you change the media/floss/polisher very regularly your tank will adjust and BB will grow on the porous stone or ring or blue water wall thing where it is supposed to.
The key is to change the replaceable cartridge or pillow stuffing regularly so the BB will build up where it is supposed to.
It's just a matter of getting your cycle going to begin with. Transfer a small piece of the old filter to the new one for a while to get things going.
 

jpm995

The obvious reason would be the bacteria that cycled the tank is dead or gone. The filter media is the usual cause. Most filters have multiple media trays, typical would be prefilter floss, sponge and maybe ceramic noodles. Changing all three at once is obviously a no no. The prefilter [if there's one] is the worse and probably discarded. We really don't know where most of the bacteria lives so alternate cleaning the sponge and noodles at separate times is safest. In my tanks i always use two smaller filters, if one dies the fish don't. I usually add a few drops of live bacteria when i clean the filter. Probably not necessary but can't hurt. Many people think the filter should be as clean as the tank but this is wrong.
 

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