Filter change

Hi, am thinking of changing my internal Juwel Bioflow M filter for a Fluval 307 external filter on my Rio 125 tank.

Firstly, am after some advice on doing this such as if the new fiter would be suitable, would it be beneficial and how I'd get the old internal filter out of the tank etc.

Secondly i'd like to know how this would atually be done in terms of the filter media & bacteria etc, - i'm assuming i couldnt just take the old filter out & put the new one in?

TIA

Just put all the media from the old filter somewhere inside the new filter, perhaps only on a temporary basis if it doesn't fit how you like it.

I think the Fluval filter would be OK, I'll leave that aspect to someone who has the filter.

I think the Juwel filters are a bit harder to remove than when I had mine a decade or so ago. With mine, I used a old kitchen knife to saw through the silicone blobs, but any flexible knife would work. Saw through the top two on one side then ease the filter box away from the glass to saw through the bottom two. Then repeat for the other side. I used a stanley knife blade to scrape off the remaining silicone. If there are fish in the tank, do this during a water change as sawing creates a tidal wave.
Be careful not to touch the corner sealant!


I assume you have fish in the tank? If the tank has been running a few years and there are a lots of live plants, there won't be many bacteria in the filter. But if it's been running just a few months, and if there are no live plants, you'll need to keep as much filter media as possible. Sponges can be cut up to make them fit the new filter. If you have cirax, that can be taken out of the box and put in a mesh bag. Squeeze as much old media as possible into the new filter and fill the gaps with new media. After a couple of months you can start removing the old media a bit at a time till you have all new.
Keep an eye on the ammonia and nitrite levels after the swap until you are sure they are staying at zero - and if you do get a spike, water changes will get the level back down to zero.

I have managed to take out my internal M Biofilter from my Juwel 180 vision tank, I used strong fishing line and got those between the sections of aquarium glue/sealant and tank glass and using a sawing motion with the fishing line and eventually got through those, takes a bit of effort for each section of glue but can be done with minimal damage to the filter housing itself.

Then you have to clean off the remaining sections of glue/sealant from the glass itself, easier said than done using lots of elbow grease but eventually cleaned off without damaging / scratching the tank glass.

And yes the external filter, Fluval 307 will be fine for a 125 litre tank, there are ways to lower the flow if it’s too much for your choice of livestock so no worries on that aspect.

Just keep the media wet in old tank water while you do the work on removing the internal filter and simply put this media into the new filter, may get a mini cycle or bacterial bloom but the bacterias should re colonise again fairly quickly.

Will you be emptying the tank first before removing the Juwel internal filter first?

I’d strongly recommend you do this with an empty tank rather than trying to remove the Juwel filter with water and livestock in the tank.

Juwel filters are usually siliconed into place into the corner of the tank, although after several decades, mine worked loose.
If your tank's well planted, then your plants will also be playing a significant role in waste management.

Whilst beneficial bacteria does live in the filter media, it also lives in your substrate and on every other available surface. In theory, removing the filter should not pose too much of a risk.

You don't really need to try and trim your established filter sponges to fit them into your new filter...just chop 'em up and stick 'em in.

Would replacing the filter help with algae? Seem to be getting a lot after just a week, light is on about 7 hours a day it’s a Juwel spectrum so dims up & down etc…

No the filter won't help. Getting the right balance between too much and too little light; too much and too little fertiliser when there are live plants helps stop algae.

In your photos it looks as though you have fake plants so any light and excess food (from fish food, ammonia etc) will cause algae to grow. With no live plants you don't need the tank light on at all, though you wouldn't be able to see the fish properly.

Rather than a new filter, what would help is floating live plants. These would cut down the light getting into the tank - and make the fish feel more secure. Floating plants don't need much in the way of maintenance other than throwing handfuls in the compost/rubbish when they threaten to take over.

What @Essjay said.

Cut the duration of the light down and make sure that you really REALLY don't overfeed. Keep vacuuming the substrate, to remove excess organic waste.

Then buy some real plants.

Back to the original question. Why do you believe you need to change the filter?
If its just about the algae others have already answered that question

seangee said:

Back to the original question. Why do you believe you need to change the filter?
If its just about the algae others have already answered that question

Click to expand...

Don’t really like the look of it in the tank currently & heard the external ones were better! Would rather have the extra tank space