Moving From 30l Biorb To 90l Tank

Hi There,
I’m new to the forum and have a couple of questions to ask after hovering and reading for a couple of weeks, I currently have a Biorb 30l but I am upgrading to a 90l tank with a new fluval U2 filter on it (I’ve inherited the tank).  Due to lack of spaceI wont be able to keep the Biorb running while the tank cycles.  I wont be getting the tank for another 4 weeks so I thought if  got a sponge from the U2 and put it in the bottom of the Biorb in the ceramic media, would enough bacteria transfer(or breed) in that 4 weeks?  Once I have the tank and have it planted (java fern and Java moss) I aim to use the water from the Biorb topped up with de-chlorinated water and transfer my current fish.  At the moment I have 2 Mollys (Male), 2 Guppies (Male) and a spotted catfish.  I also intend to use the current ceramic media (initially) under the sand to help transfer bacteria, then just keep an eye on the water.  My local water is very soft 3.675 Clarke.

Analysis    Typical Value     UK/EU limit   Units
Hardness Level   Very Soft      
Hardness Clarke   3.675            Clarke
Aluminium   <6.77   200   µg Al/l
Calcium   17.0      mg Ca/l
Residual chlorine - Total   0.62      mg/l
Residual chlorine - Free   0.55      mg/l
Coliform bacteria   0   0   number/100ml
Colour   <1.64   20   mg/l Pt/Co scale
Conductivity   142   2500   uS/cm at 20oC
Copper   <0.0049   2   mg Cu/l
E.coli   0   0   number/100ml
Iron   <11.5   200   µg Fe/l
Lead   <0.328   10   µg Pb/l
Magnesium   2.37      mg Mg/l
Manganese   <0.486   50   µg Mn/l
Nitrate   5.95   50   mg NO3/l
Sodium   11.3   200   mg Na/l

^^ If you can make sense of that, it wont let me upload the picture.

Also I will be moving my bogwood, half dissolved shell and a few other stones to the new tank when I do the initial set-up.  Once the new tank is running I hope to add some of the sponge from the biorb into the new filter.  Hopefully this should help me to get then new tank cycled as soon as possible once the transfer has taken place.  I would be grateful for any comments if I’m going wrong or suggestions please.
Regards
Andy

Hello Andy, and welcome to the forum.

You're doing exactly the right thing with your transfer of media ideas. Just check your Ammonia, Nitrite and Nitrate levels carefully for the first month after the tank move, and don't get any more fish until you're sure the filter is working properly.

Talking of fish, I'm afraid, mollies and guppies are hard water fish so it's best not to get any more of those. If you browse the Fish Profile section on this forum you'll see a Hardness range given and they are both m,h,vh while your water is vs. There're loads of fish suitable for your water, but very soft water comes with it's own set of problems. My water is equally soft.

EDIT: PaddyC just pipped me, and has said a lot more and better of what I've just said, but I'll leave it as is.

Hello Andy and welcome to the forum. 

Livebearers and your soft water have already been mentioned.
Fish websites use one of two hardness units - german degrees (also called dH) and ppm CaCo₃, which is usually called just ppm.

Your 3.675 deg Clarke convert to 2.9 deg German and 52.5 ppm. Use these figures on sites like Seriously Fish and FishBase

The bacteria we want to grow live on every surface in the tank - the glass, the substrate, the decor on the heater etc. They grow best where there is a good flow of water - inside the filter is the best place for this.
I suggest you move everything you can. Even if the decor is not part of your long term plans for the new tank, in the short term they will help as there will be some bacteria on the decor.
The U2 filter has 2 sponges, 2 poly-carbon pads and a box of ceramic media. I think the ceramic biorb rocks are too big to fit inside this box. But the sponge from the box in the biorb can be 'persuaded' to replace the poly-carbon pads with the aid of a pair of scissors.
If you could get any of the smaller stones inside the U2 that would be a great help. How hard are they, can they be broken into smaller pieces? If the answer is yes, I would smash up as many as would fit inside the box in the middle of the U2 then do as you suggest with the rest in a mesh bag. After a couple of months start removing the stones in the bag a few at a time, then replace the broken  stones bit by bit with the proper U2 ceramic medium.

A master test kit is definitely a good idea. Feed the fish lightly for a few days before the swap, nothing on the day itself, and lightly for a few days afterwards. Test for both ammonia and nitrite until you have a week of them both zero. If you do find either or both drifting above zero, water changes are the best way to keep them down. If you have a low pH to match your soft water that will help keep the ammonia in the  less toxic ammonium form, but nitrite will be more toxic.

I know it will be hard to resist but if you could manage to wait a couple of months before getting more fish you will do yourself and the current fish a big favour.



What kind of catfish is whiskers? if you don't know, a photo could help with an ID.

I see why you want a bigger tank! And a standard shaped rectangular tank will have more swimming room than a spherical tank.

Hi All, just an update on where I'm at at the moment with the upgrade, before getting the new tank, I got the filter foams from the U2 and put them in the Biorb under some of the gravel for 3 weeks, they were pretty filthy when I got them out so they got rinsed in some of the Biorb water removed after a water change.

When I got the tank (last week) I set it up how I want it and removed basically everything from the Biorb.  I managed to half fill the bio section of the filter with the biorb stones so I have a half/half mix in there at the moment, let the tank run for 48 hours with the plants and decorations in it.

I have now moved the fish and put the remaining Biorb stones in a mesh bag at the back of the tank behind some plants and the filter.  I have been testing the water daily and am getting 0 Ammonia, 0 Nitrite and what looks to be a slight increase in Nitrate, so I think that by moving all the media accross may have done the trick.  The fish have now been in the tank for 5 days and I have never seen them so animated, I dont think they have been still since the change.  I initially thought some of the smaller ones may have struggled in the filter current after being in the Biorb but they seem fine.  And even more amazingly whiskers has found a new niche in life - digging up plants!!  Here is a link to some shared photo's (I couldnt get them to upload) https://goo.gl/photos/CWSrk3UGSjL6Dwp36
Please excuse the quality, I'll try and get some less blurry ones later.

Fantastic news about the tank. 
Great pictures. Whiskers is adorable. 

That's the trouble with male livebearers, one track minds  This is the reason it is always advised to have 1 male to 2 or more females.

All livebearer males look like females until puberty. Something to watch for when your fish have babies.

I'm sorry to hear about your fish 
It's curious that neon tetras have survived as they are usually such delicate fish.

When you set up the external, put as much of the established media into it as you can. Leave out some new media to make room. Afterwards, monitor your ammonia and nitrite until you are sure they are OK. The new filter should have settled in by the time you get more fish.

If you intend removing the old media at some point, I would wait till after you've restocked the tank fully, then remove a bit of old and replace with the media that was supposed to go in the filter, one small bit a month. Or just leave the old media in there.