Need help with planted tank

[Bangwalldie]

Do I need to top up the soil if they decrease ? Currently my soil is at 6cm. And, Monte Carlo or glosso would be a good carpet ? And any other carpet plant that will grow well in low tech tank ? (Besides moss,mini pellia, mini fissiden)

[Urban Aquaria]

You can top up soil anytime whenever required, usually its to shore up eroded slopes and such... though once the plants cover the substrate you wouldn't be able to top up soil as easily anyways (unless you remove the plants, top up soil, then re-plant again), so most people just leave it be.

Monte carlo and glosso are okay carpet plants for low-tech tanks, just that their growth rate will be much slower than compared to a high-tech tank with Co2 injection.

You can also try other plants like marsilea hirsuta or hydrocotyle sp. japan, they could work too.

[Bangwalldie]

Is 6cm of soil adequate ?

[Urban Aquaria]

Is 6cm of soil adequate ?

6cm of soil depth is sufficient, deep enough for most rooted plants (small carpet plants like HC, monte carlo or glosso can even grow in just 2-3cm of soil depth, their roots tend to be very shallow)... though on the other hand, if you plan to add larger rooted plants like Echinodorus (especially the larger varieties), then a deeper soil bed may be better as they create very large root systems.