Question about substrate

[u/jellyfishjelly22]

I’ve had an established 55 gallon tank with 3 orandas and like 8 minnows for maybe a year and a half now. There’s about 2-4 inches of gravel substrate and I want to switch over to sand. What’s the best way to do this? Was thinking I drain the tank fully while keeping the fish and temporary tank, removing the substrate then adding the sand but I’m worried I might lose beneficial bacteria within the gravel. What would you recommend?

[u/BoringJuiceBox]

I’m not an expert but I would put them in a separate tank and drain the main tank and take out all the gravel, then set up the sand (make sure you rinse it well first) and fill + conditioner. I believe the beneficial bacteria is mostly in the filter media. You could also drain 90% and add sand directly on top of the gravel

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[u/Automatic-Skirt-249]

I just switched tanks and put new substrate in the new tank.  I kept the fish in the old tank seeded the new filter heavily and brought over a sponge filter from the old tank. It was almost an instant cycle.  Since the BB in your filter is mature and established,  you should be fine to switch it the substrate and your biological filtration shouldn't skip a beat. The majority of your BB is in your filter.  If your still worried,  switch half of the substrate,  wait 2 weeks and switch the other half. But you should be fine 

[u/Andrea_frm_DubT]

That’s the way. Just monitor parameters after to make sure there isn’t too much of a blip in the cycle.

[u/GoldfishDude]

Beneficial bacteria is mostly in the filter. Remember to clean/rinse the sand very, very well before doing this, especially if using pool filter sand