Switching From Under Gravel

[Robert 208]

Hi

I have a 20 gallon (UK) hexagonal tank. I want to switch from power head driven under gravel filter to a cartridge type filter/pump. I also want to switch from 3-4mm gravel to sand mixed with 1mm gravel.

How long should I run the new filter in the tank before I can remove the gravel, under gravel filter base disc and the power head?

Can I speed this up?

Hope someone can help.

 

[rdd1952]

Hello Robert and welcome to the forum.

I don't have any experience with UGFs so I'm not sure about the gravel issue. Usually, I would say to run the 2 filters together for about 2 or 3 weeks before removing the old one. That still may be the case but I'm not sure.

As for changing substrate, I have done that and it went well. The difference being that since I didn't have a UGF, there was very little bacteria present in my substrate so I didn't experience any mini cycle from the change. It your case, that will be different as your gravel will probably contain quite a bit of bacteria.

Here are my thoughts on it (anyone feel free to shoot holes in this if you think it won't work). Put the new filter in the tank and turn it on wide open. Turn the flow down some on the old UGF (maybe reduce by 2 to 25 percent). Do this about every 4 or 5 days until you have lowered the flow of the UGF as low as it will go. Leave it another 4 or 5 days and then remove it. Naturally, if your UGF isn't adjustable, this is all pretty much useless. Anyway, once you have been able to do this (keep a check on your water parameters to make sure you aren't getting ammonia or nitrite spikes), your new filter should contain most of your bacteria and the bacteria that was in the gravel should be greatly reduced making it possible to change it to sand without much problem.

Try asking this in the Chit Chat sectin and you will get more feedback from people that have more experience with UGFs. Good luck.

 

[Robert 208]

Hi

I have a 20 gallon (UK) hexagonal tank. I want to switch from power head driven under gravel filter to a cartridge type filter/pump. I also want to switch from 3-4mm gravel to sand mixed with 1mm gravel.

How long should I run the new filter in the tank before I can remove the gravel, under gravel filter base disc and the power head?

Can I speed this up?

Hope someone can help.

Thanks for that. Yes you are coreect the UGF is unadjustable. I thought I could switch it off for a couple of hours per day and leave the new one running?

 

[rdd1952]

That would probably work. Just make sure you don't forget to turn it back on.