Changing out substrate?

[limari]

Hi! I have a 45g cycled tank, lightly stocked with gold pristella tetras, danios and a small school (7) of panda corys. The substrate I have now is medium-sized gravel. It's really not good for my corys, so I'd like to change out the substrate to a smaller, rounded gravel: bigger than sand, but much smaller than the gravel I have currently. My question is, how can I change out the substrate without crashing my cycle and stressing out my fish? Any suggestions/methods would be greatly appreciated!

 

[Aiken Drum]

I presume you want to do all this in a tank full of water with fish in place?

It may be possible to syphon out your gravel. If not, scoop it out carefully with a net.

https://youtu.be/pa3U7GuNI7M

You can add substrate back into a filled aquarium using a plastic bottle. Ive done this many times, also useful to "top up" lost sand and other fine substrate.

https://youtu.be/IQMBGzlteK0

Do it in stages, like 25% one week, 25% the following week to minimise disruption to your cycle.

 

[limari]

Great advice! Thanks!

 

[Aiken Drum]

Ive never tried syphoning out gravel, but ive syphoned out sand. The guy in the video manages it OK though, but your gravel size might be too big.

If removing gravel kicks up a lot of sediment might want to follow it up with a water change and regular testing to ensure you dont cause a spike of anything.

Let us know how you get on.

 

[gilpi]

The substrate won't change the cycle. I've changed gravel with fish in tank more than once, it will be a bit messy and the water might be cloudy for a day or two but it will settle.

 

[jake37]

What i have done twice in the past year for my 29:
fill 30 gallon pail used with fishes night before and put some prime in it
spread garbage bag under tank as a drop sheet in case gravel or water spill
(i use one of those large heavy duty black ones - quite large if you split them open)
Grab two 5 gallon pails dedicated for fish use (they are like $3.5 each):
Fill each with about 2-3 gallons of water. Put plants and decoration in 1 and fishes in the other (for hard to catch fishes i wait till i've partially drain the tank; for kuhli loaches i wait till there is only an 1/2 inch of water left in the tank. Drain the tank completely. Use a dog scoop (one that is used for feeding a dog - but any large hand held shovel works). Shovel out old substrate completely. Put in new substrate. Fill tank about 1/2 way. Put in decoration (in my case plants and drift wood); finish filling tank about 90% full. Make sure water in tank matches temp water in pail (this was easy because i filled a 30 gallon pail the night before with water so it was already at room temp) - put fishes back in tank - measure ammonia next 3 days in the morning to make sure cycle is fine (it was - i use sponge filters). This is the tank which i changed 3 or 4 weeks ago - also gave me an excellent chance to do an inventory count on fish - happy to report no one has died in the past 14 months:
--
In case it matters the inventory is:
3 mystery snails
2 nerite snail
2 l204 (there were 3 but when i change the substrate i put the larger one in the 120)
2 super red bn
1 l333
4 hongsloi
1 nijjensi
5 sterbai
7 kuhli loaches