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Changing gravel to sand in 3 year old tank??

Wed Apr 29, 2020 2:31 pm

Question on changing gravel with established bacteria to cichlid sand. My 36 gallon bow with 8 adults and 7 juveniles recently went under a huge cleaning due to 6 weeks of deferred maintenance and tons of glass and rock surface algae. My Eheim 2217 was also down to a trickle so impeller was pulled and cleaned. Now in tip top shape (see pic below) and ready to put rocks back in and my new 3D background.

First, seems like a good time to change out my 3 year old black grand to cichlid sand. My biggest fear is that this is where most of the beneficial bacteria live (aside from filter). The filter media was also thoroughly rinsed so possibly some bacteria lost in that process.

1) Can the gravel be changed/replaced without losing all the beneficial bacteria?
2) Can I add sand with the tank already filled with water?
3) Any reasons for or against the sand vs existing gravel?

Re: Changing gravel to sand in 3 year old tank??

Wed Apr 29, 2020 6:51 pm

What are your test results for pH, ammonia, nitrite and nitrate now? Better to ensure you don't already have a problem before you add to it by changing gravel.

That is a LOT of fish for a 36G bowfront so you could be overloading your biofilter. No rocks??

If the results are all zero except for nitrate, and if that is zero, you could remove the gravel with a clean dust pan into a bucket. Keep it wet with tank water because you will be using it.

Add the sand.

I prefer to remove the fish, but it can be done with the fish in.

Use the gravel from the established tank as much as possible in the filter media trays. What is left bag in aquarium safe mesh and rest the bags inside the tank initially. Test ammonia and nitrites...if they are at zero for several days you could gradually remove the various gravel bags.

Re: Changing gravel to sand in 3 year old tank??

Wed Apr 29, 2020 7:55 pm

Thats great advice, DJ. I would have just said don't do it haha

Re: Changing gravel to sand in 3 year old tank??

Wed Apr 29, 2020 8:21 pm

Good advice on using some of it gravel in the filter media basket. The fish count is actually 3 less adult peacocks as I know the tank is getting quite cramped. I always wanted to overstock but once the juvies get bigger it will be pushing it. I have a lot (maybe 12 pieces) of gray rock in their which is currently covered in algae as well. It is being cleaned in a 1:10 bleach to water bucket for 15vmin and scrubbed then two 24 hour rounds of sitting in bucket with dechlorinator before returning to tank.
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