Adding substrate to established tank

[Kutlwano Dikgasu]

Hi everyone. I have a 4ft aquarium with 5 angelfish, 4 rummy nose tetras, 4 corydoras and a lot of snails. Its been running for 2 years at my old apartment and almost 4 months at my new one, when moving I almost did not disturb the 4mm (4cm tall) substrate. The substrate has become really really dirty, beyond the point of gravel vaccuming because I never vacuum it. I want to start over so I'm thinking about adding pool filter sand over the current substrate. Is this a good idea? And what will it mean for the bactaria in the old substrate. Are there any consequences to adding new substrate to a "established tank"?

The are some plants in the tank (10 vallisneria spiralis and 2 crypts, one just starting to show) and two sponge filters.

 

[JettsPapa]

Hello, and welcome to the forum.  I don't see a problem with adding a layer of pool filter sand.  While that might kill some of your beneficial bacteria (and I'm not at all sure it will), there should be enough in your filter and on the other surfaces in the tank to quickly catch up.

You might need to raise the plants after adding the sand.  They may not like suddenly being buried deeper.

[Kutlwano Dikgasu]

Okay, thank you 🙂

[darkG]

I guess there is a risk that the gunk in the old substrate rots if it's trapped under new substrate and circulation stops. 

[Kutlwano Dikgasu]

Yeah, there's quite a lot of gunk. I could also just add the new sand and use seachems stability to cycle the tank with  fish in?

[Wrencher_Scott]

On 3/2/2022 at 10:24 PM, Kutlwano Dikgasu said:

Okay, thank you 🙂

I'm with @darkG, if it's that dirty you are most likely going to trap old food, poop, ect under there. Can you not just gravel vac it real good? 

Just FYI stability is not some magic cure all. Your filter's beneficial bacteria will take care of everything, much more than the gravel. Assuming you kept the filter wet going or at least didn't let it set too long. 

This whole thing is like sweeping the dirt under the rug, but worse because it's not just dirt. 

I do love sand though, all the poop and old food stay on top. Easy to clean when it's water change time. 

Good luck 🙂

Edited March 4, 2022 by Wrencher_Scott