Is ph a problem in malawi?

[zenith4]

hi everyone, so i've got a 4ft tank and i'm looking to keep malawi's, been given a load of brown lava rock from an old tank - never used this stuff before, it's really weird, like pumice stone, airy and light. used to keep malawis about 10yrs ago, used ocean rock and coflake sand to bump up the ph a bit, but that was in a different location, now i've got tap water with a ph of around 8.

got a few questions for you all:

1, do i really need a sand substrate with malawis? i'm looking at using black 2-3mm gravel instead of coflake sand, which always seems to turn green. if i do still need sand, is there a black sand option available?

2, has anyone else used lava rock in their tank? sounds daft, but do i need to weight it down to stop it floating? previous owner glued pieces together with silicone.

3, are there any safe plants i can use to break up the tank a bit? i know malawis are from a pretty plant-free environment, but there must be something that'll survive. any ideas?

[zenora]

You'd probably get some top notch advice in the old world section, but I reckon you'll be alright with black gravel or sand, yeah there's black sand available.

I've heard Anubias might just survive with Malawis, worth a shot I suppose.

[lake4fin]

Most substrates are fine for Malawi's, just bear in mind the finer the better as they do like to sift through it. I've used lava rock before, it's not the most visually appealing in my opinion, but it does the job. If you're looking to add some plants, you might want to try Java fern or Anubias as they can be quite hardy. Onion plant is another option, although even these can struggle to cope with the conditions in a Malawi tank.