[Byron]

Welcome to Tropical Fish Keeping forum.:wave:

On the GH and KH, just contact your municipal water supply folks; they likely have a website, and this information may be posted. Or if not, they can tell you. Knowing the GH is important, and the KH too as it will tell us if the pH is likely to lower or not. Some fish have very specific requirements in GH and pH, as the profiles will point out.

Glass Catfish is one, as the profile will tell you. As for the Clown Loach, my advice is to return these now before they get settled and develop problems. Fish grow continually, and this species will attain 12-18 inches, but when they are growing in too small a space, they do not develop properly. Internally they can be stunted, or at the very least stressed which causes other health problems. Much better to return them now, as later may be too late for them.

Your light is fine for plants. Below is an old photo of my 29g with this same single T8 Life-Glo tube. The plants are all low and moderate light requiring, they are in our profiles too.

Byron.

 

[Byron]

On the water numbers, it seems to vary depending where your water comes from. But generally speaking, the GH seems to be in the soft to moderately hard range. The Alkalinity (KH) is comparable, which means the pH will not likely lower much if at all in the fish tank.

As for the plants, there is chain sword (planted in the sand), Java Fern on the wood at the left, and Water Sprite floating. Click the shaded names for the profiles with photos.

Byron.

 

[Byron]

What other species would go wll with the Glass Cats? I would like to maybe get 6 Neons and another small school of something else if possible.

I would up the neons, say 8-9. "Six" is the usual minimum number mentioned for tetra, but if space allows then having more will always be better for the fish and you. The more there are, the more "relaxed" and normal the fish will feel/behave, and that means you will see them as nature intended, interacting, brightly coloured, etc.

Can't remember if it was mentioned earlier, but make sure there are floating plants, lots of them, over these fish (Glass Cats and neons, and other forest fish). Water Sprite is ideal for this. Fish love its dangling roots, it is attractive, and a good source of microscopic food.

If you read the data in the Glass Catfish profile, it mentions slow-flowing shaded streams as the habitat, so suitable fish will be those preferring a similar environment. The neons fit this. Others might be rasbora such as Lambchop Rasbora or Hengels Rasbora, even the slightly larger closely-related Harlequin Rasbora; Lemon Tetra would add a bit of different colour to the tank. Loreto Tetra. Marble Hatchetfish or Black-Winged Hatchetfish--these two in the Carnegiella genus are smaller and quieter than the larger Silver so a better choice. You mentioned the Black Widow earlier, and as Izzy noted it is a bit boisterous, but something along similar lines in appearance is the Black Phantom Tetra.

I don't think the tetra I've mentioned are likely to fin nip the Glass cats, provided the tetra are in a decent-sized group, 8 or so of each species selected.

Byron.

 

[Byron]

Water Sprite will be fine wityh the water at the tank frame level. And you thin it weekly by removing the daughter plants from the leaves after they form, and discarding the largest plant(s). Once you get into the habit, this keeps approximately the same amount of coverage. Obviously any floating plant will lessen the light getting to the lower plants, but given the benefit of floating plants to all forest fish, you select lower light lower plants, like Java Fern (and mosses on wood, etc), chain sword or pygmy chain sword, crypts, Anubias.

You've room for groups of perhaps 3, 4 or even 5 fish, depending what the species are. If you don't get the Glass cats, your options open a bit. Profile explains this.

Byron.