What Media Should I Use To Jump Start My Cycle?

[mbriggs84]

I have a mature 29 gallon tank with a HOB power filter. I just got a 90 gallon and I'm beginning my fishless cycle. What exactly should I be using from the old tank to jump start my cycle?

 

[waterdrop]

You can safely use about 1/3 of your biomedia (biomedia in most HOB filters is the main sponge, although it could be other material, but it is the media that has the most surface area for the bacterial films to attach to.

So the usual technique is to first obtain a new sponge or biomedia that matches what you put in your HOB. Let's say it's a sponge. You'd take scissors and cut off about 1/3 of the new sponge. If it were me I'm look at the water path through the HOB and select the first third that the water flows through.

Before the actual introduction of the mature media to the new filter that is on the 90 gallon I would already have my fishless cycle under way. That way you've already obtained the correct ammonia and know how to measure it, you're already sure the temperature is up to 84F/29C and that you've got some good surface water movement from your spraybar or whatever. In other words you kind of know what you're doing so that you are less likely to waste your precious mature media.

So all that is up and has been going say for a few days and then you go ahead and shut down the filter and pull your biomedia out of your old tank and into a container of the same tank water it has been in all along (or you just do the operation quickly while everything stays wet, but it is better to pull it to a container and use the scissors underwater so that if some household thing distracts you you won't accidently let it dry out. You match that 1/3 piece of new media next to the mature media and make your cut. It is better for the resulting pieces to be very slightly too big so that they will make good contact with each other once they are back in your HOB. The 2/3 mature media that is then left running your older tank should not cause a mini-cycle but you should be testing ammonia and nitrite to make sure it stays ok.

Meanwhile you of course make some sort of cut or make room for the 1/3 mature media within the media of the new filter on the 90G tank and again you ideally want the mature stuff to be in the earlier part of the water flow. Make sure your ammonia concentration is 4 or 5ppm if you are at the early stage of your cycle and then just follow standard fishless cycling per RDD's article.

I've tried to describe a kind of ideal situation but be aware that the really important part is simply that mature media somehow gets from an old filter into direct contact with the media in the new filter, that is what is really important and sometimes you just have to be creative to help that happen.

If your testing (with your liquid test kits of course) shows any increase in ammonia or nitrite(NO2) in the old aquarium then you must be prepared to use good "fish-in" cycling technique and do some water changes for a period of time until your levels get back to zero.

Good Luck!
~~waterdrop~~

 

[OldMan47]

I fully support WD on cycling. Lately he is the "expert" here on TFF. If you can spare 1/3 of your filter media for cycling a new tank, most of us can, it is a great starter. If not, for whatever reason, I have found that I can cycle a new tank by using it as the cleaning bucket for an established filter and then finishing things up by doing a fishless cycle on the new tank. It is a bit messier than simply using a sample from my old filter, but a week for a cycle on a new tank strikes me as a good compromise. If you choose to go that way, don't forget how messy that new tank will look until you vacuum it with your water change gravel vac.