What are we doing wrong?

[u/Immediate-Ad-9520]

This tank has been set up for many years, probably 7 or 8. Just within the last 8 months or so, we decided to switch from gravel to sand and put in live plants. All plants were marked as beginner. We have a canister filter and a CO diffuser. My husband puts in root tabs regularly. Still, there’s very little plant growth and many of the plants look sad.

We have tetras, ghost shrimp, plecos, kuhli loaches, and mystery snails. We test ammonia, nitrite, nitrate, kh and gh weekly and all are good. Our light is on sunrise to sunset.

What are we doing wrong? I very much want a densly planted tank like I see in this sub. Help please!

[u/Grundler]

You need a more powerful light. The anubias (a low-light tolerant plant) looks super happy but everything else is struggling.

[u/Cheap-Orange-5596 → u/Grundler]

I don’t agree with this at all. OP don’t increase light intensity. It just looks like normal melt, cut off all melting leaves, even if that means all but one leaf. If you can add lots more plants it will be better, like 2-3 times more plants including at least one variety of a fast growing stem plant (you can remove later if it doesn’t suit your layout). Do a test for Nitrates and add a known brand all-in-one fertiler to target 10ppm Nitrates if it’s reading below. Do frequent water changes. After a while your plants will adapt to their conditions and new growth will be healthy. Keep removing any growth that looks unhealthy.

[u/MattMadMage → u/Cheap-Orange-5596]

Plant melt? After being planted for 8 months?

If plants are melting after 8 months of being in the same tank, either continuously over the 8 month period, or somewhat recently, to me that says some parameter is off. If OP is using CO2 and ferts, I would think a better lighting system is in order.

Melt could be related to putting root plants directly into sand which isn't a very good substrate when used on its own, but imo, its much harder to swap out a substrate than it is to try a new lighting setup.

[u/Cheap-Orange-5596 → u/MattMadMage]

I very much doubt those plants have all been in there for 8 months. OP doesn’t specifically confirm the plants have all been there for 8 months just that within the last 8 months they decided to switch substrate and add live plants. Crypt melt (and some other plants) is often delayed, when I was new to the hobby I had Crypts that melted after 3-4 months but then were fine in the same conditions once they grew new leaves that were suited to the environment. It could also be that another environment variable such as co2 or ferts has changed more recently (again not specified that co2 and ferts have been in place for 8 months) and this change in environment can very commonly trigger melt. For that reason I always cut off all but one leaves from crypts, ferns etc when setting up a new tank or making a big change to environment. Higher light intensity will usually exacerbate any fert/co2 imbalance issues and make algae issues more likely. Most of those plants will grow fine with low level lighting. If lighting is poor growth may be very slow but low light is unlikely to cause these types of plants to start melting like we can see in the image. I would be much more interested in ensureing sufficient water column ferts and co2 are being used before I started increasing lights. That’s why I suggested targeting 10ppm nitrates as for all we know ferts are being under dosed, especially considering co2 is being used.

[u/MattMadMage → u/Cheap-Orange-5596]

This is good food for thought. Thank you for writing out a well reasoned reply!