I am about 30 years in. This whole nitrate levels crap is all a very new fad. Oceans have almost no detectable nitrates, so you tell me what they like. Now with that said I have had success in both dirty and clean water, but dirty water often tips the scale into crashing if you let it go to far. The only spawning event I had was with 100% clean water with no nirates at all. Lets put this into perspective, hammers like both, but like is the key word. They will not do poorly if they just dont like something. If you are having issues nitrates are the last thing I would look at. Most of the time a large 50 to 100% water change corrects most issues. Provided the problem is not lighting. The image below. I started with 5 heads of branching hammer and 3 heads of frogspawn. 2-3 years after that pic the hammers outgrew the 210g tank and hit the glass and top of the water.I can try and keep them in the middle of the scale.