Cycle Bump After Cleaning Hob Filter

I have a 20 gallon tank which is fully cycled with an AquaClear 30 HOB filter. After I clean the filter, the nitrite-to-nitrate conversion stalls and I start getting measurable nitrite for a few days. In the AC 30, I run the filter 'sponge', some thin poly sheets, and biomax media. While cleaning, I thoroughly rinse (vigorous squeezing) the filter sponge in aquarium water and/or treated (and same temperature) water. I replace the poly sheets, and the biomax remains in aquarium water or treated water the whole time.

Is this normal for those of you using AC filters? Years ago, I was using a Marineland HOB filter with a bio-wheel, and this never happened. I'm assuming that bio-wheel keeps a more established BB colony.

Any tips to keep this from happening?

Thanks.

 

Hmmm that is a good one. Let me preface my response. I have a well so no chlorine. I go crazy on my sponge under the tap in sink. The bio media I just rinse and I have never noticed anything change. Granted I don't test as often as I should but I see no indications from the fish to any problem.

 

In my experience, the following strategy helped preserve the cycle. (You may do some of these steps already, but I'll include all of them):

Turn off the filter when doing the water change/cleaning the filter.
When finished, add back dechlorinated water to the tank. If using a water changer, dose the conditioner for the entire tank volume, not the amount of water changed.
Then:
WAIT 20-30 minutes before restarting the filter. This ensures that thoroughly mixed and conditioned water starts flowing through the filter media.

Yes, I know that the manufacturers say that the water is instantly conditioned the moment their conditioner hits the water. But I was having minI cycles, and when I waited before restarting the filter, they stopped.

Hope this idea works for you.

 

Are you using the bio-max that came with it, or have you added more?

Here is how I load one of my AC30's....

AC30 media basket 1

• Islandvic
• Nov 18, 2018

AC30 media basket 2

• Islandvic
• Nov 18, 2018

I cut down the sponge slightly to make room for more media.

I have one of these ziptied to the end of the intake tube....

Top Fin Sponge used as pre-filter on intake tube

• Islandvic
• Dec 24, 2018
• 1

Top Fin MF20 Internal Filter replacement 2-pack sponges, perfect to use for a pre-filter on your...

I alternate cleaning the prefilter sponge and the media in the basket.


I actually run 2x AC30's on my 20g. I turn them down half way to reduce flow and for the water to bypass internally to make extra passes through the media before discharging back into the tank.

No nitrite spikes for me.

I also don't clean both at the same time.

 

Are you cleaning the filter and doing a water change at the same time?

 

I go crazy on my sponge under the tap in sink. The bio media I just rinse and I have never noticed anything change. Granted I don't test as often as I should but I see no indications from the fish to any problem.

Well, that lets me know that I'm not over-rinsing the sponge. Thanks.

In my experience, the following strategy helped preserve the cycle. (You may do some of these steps already, but I'll include all of them) Yes, I know that the manufacturers say that the water is instantly conditioned the moment their conditioner hits the water. But I was having minI cycles, and when I waited before restarting the filter, they stopped. Hope this idea works for you.

I don't clean the filter the same time I do water changes, but that makes sense. During water changes, I typically just dose the recommended amount for the additional water. Is there any downside to over-dosing like you are recommending?

Are you using the bio-max that came with it, or have you added more? I also don't clean both at the same time.

Thanks for the detailed relpy! I am actually using twice the amount of bio-max that came with it. Our filter setups are somewhat similar, except I am using the whole sponge media. I can definitely see how using two AC30s would help stabilize things. With the two, how often do you have to wait before doing a water change? And, what is your fish load? I am going to get a prefilter sponge as well. I bet alternating rinsing the prefilter sponge and main sponge will help. Thanks.

Are you cleaning the filter and doing a water change at the same time?

No, I alternate between water changes and filter cleanings with days in between.

 

Well, that lets me know that I'm not over-rinsing the sponge. Thanks.



I don't clean the filter the same time I do water changes, but that makes sense. During water changes, I typically just dose the recommended amount for the additional water. Is there any downside to over-dosing like you are recommending?



Thanks for the detailed relpy! I am actually using twice the amount of bio-max that came with it. Our filter setups are somewhat similar, except I am using the whole sponge media. I can definitely see how using two AC30s would help stabilize things. With the two, how often do you have to wait before doing a water change? And, what is your fish load? I am going to get a prefilter sponge as well. I bet alternating rinsing the prefilter sponge and main sponge will help. Thanks.



No, I alternate between water changes and filter cleanings with days in between.

Okay. Dont clean both at same time. Too much at one time

 

I don't clean the filter the same time I do water changes, but that makes sense. During water changes, I typically just dose the recommended amount for the additional water. Is there any downside to over-dosing like you are recommending?

It depends on how you refill the tank. If you use a bucket, you can add the specified drops to the water volume of the bucket.

If you use a python or other hose attachment, you'll need to dose the amount of the whole tank (as per the manufacturer directions for Prime, for example). That's because the water from the hose has not been conditioned before going into the tank.

 

It depends on how you refill the tank. If you use a bucket, you can add the specified drops to the water volume of the bucket.

If you use a python or other hose attachment, you'll need to dose the amount of the whole tank (as per the manufacturer directions for Prime, for example). That's because the water from the hose has not been conditioned before going into the tank.

Ok, I'm on the same page now. I just use a standard siphon from the ol' 5 gallon bucket to the tank, so I just dose that.

 

I still do water changes every 7-10 days.

I usually drain around 8 gallons (2 trips with my 5 gallon bucket) each time, so 40%.

I do a gravel vac each time.

Usually I will swish the pre-filter sponges around in the bucket of tank water during water changes, which seems to extend intervals of cleaning the media in the main basket.

My other AC30 has less bio-media in it, but has a 100ml bag of Purigen also. I'm actually recharging it right now.