I have been keeping goni's for years and I have low phosphate and nitrates..
The main problem with most goni's is they are very hard to keep and some are still impossible like goniopora stokesi..
Some like the ora red goniopora actually are not to bad at all to keep and do well with very few feedings.. The general rule is red goniopora and encrusting are the easiest and the greens are hard.. Some of the blue and purple are in-between. Of coarse there are exceptions to the rule..
Most goniopora requires food. BBS, cyclopeese, golden pearls, oyster eggs are good foods.
Another issue is they are all different. Some like low light some high light and some like medium, some like low flow while others like strong and others are in-between... That is what makes them hard really trying to find out what they like.. Sometimes it just takes a couple days for them to fully open too, they are touchy. Some I just stick my finger in the water and they close up...