I've experienced that spider plants cannot compete with pothos for nutrients. They do fine alone, as the only emergent species. But all my spiders turned white and slowly died when used in systems with pothos. Only one remains in my 55g and it's looking like a zombie. You can see it right in the center, to the left of the vase/light in the first pic I posted above. Yes, it could be my tap water, or the lighting, or the brands of fish food I'm using. But why cry "zebra" when it's probably just another horse?