[Suicide Junkie]

The Grome are reputed to be good at ground combat - well so are my Gaim and I wanted a match up. I invaded the Grome's only sector (they were in the game as a Neutral) with an impressive force of 20 Heavy Destroyers, 18 Light Cruisers, 3 Light Carriers (each carrying 120 Light Fighters) and 3 Light Transports (each carrying 1500 Elite Light Infantry with Mk I Infantry guns). I headed straight for the Homeworld. My losses to their defences were 4 Light Cruisers and approx 1/3 of my fighters - but it was the ground combat I wanted to see. The first transport landed and I watched at the 1500 troops were slaughtered by the Grome's 2000+ Light Infantry - but they did kill over 500 of the foe. The second transport grounded and again my entire force was wiped out - but the foe was down to under 700 Infantry and 80 Militia. The final transport dropped and the battle field was finally mine - with a mere 600 Infantry left of the 4500 I came to this battle with.

I'm wondering about this... taking a homeworld in one combat is a little quick, don't you think?

I suggest the following settings changes:
Defending Units Per Population := 1
Population Defender Attack Strength := 1
Population Defender Hit Points := 20
Number Of Ground Combat Turns := 2

For one, this will let you drop reinforcements before the entire contents of your first transport is wiped out.
Two, it will make homeworlds take much longer to secure compared to colonies. The militia's attack strength is not significantly affected, but they have many more hitpoints, taking longer to root out.
(See Centauri occupation of Narn)