Topping Substrate vs Replacing Substrate...

[chadcf]

I have an established 125 gallon tank that is currently using a black diamond blasting sand substrate. After being unable to keep cories alive in the past 18 months I am starting to suspect the substrate is too sharp and harsh on them (this seems heavily debated, but I have lost many due to what appear to be fungal infections around the gills/fins and they also seem to lose their barbells).

I am thinking of putting 20/40 pool filter sand in instead before restocking more cories so they can be a bit safer and have a nice substrate to sift through, plus aquarium sand like CaribSea or something would cost a small fortune for this much...

Now is the big question. It's heavily planted... And a pretty big tank. Can I get by with topping the black diamond sand with say an inch of pool filter sand? Or will the finer sand eventually work it's way down into the cracks? The prospect of removing all the plants and substrate and putting all new substrate in seems very daunting and like it would stress my fish out a lot more.

 

[GlennO]

An inch thick layer should last for a while but eventually you'll start seeing some black sand on top. It depends how much it is disturbed. If you're like me you will occasionally want to uproot plants and plant new ones and that process brings some lower substrate to the surface.