I've been running Ammonium Chloride now since March 10th, just over 2 weeks.
Since switching from dosing Nitrate, which at the time I was under-dosing at 1ppm per litre per day, due to a mishap pushing my nitrates higher than I'd like. I switched to Ammonium Chloride and set the dosing amount to be approximately the same, and have slowly worked it back to where I was with Nitrate dosing (about 6.5ppm per litre per day)
Considering I rarely if ever feed the tank and it runs on inputs of chemicals, the change was extremely stark - clumps of hair algae and film algaes on the tank died back, cyanobacteria died back very very heavily and the overall coral health (evidenced by polyp extension, growth and thickness of coenosarc) improved drastically.
In terms of actual observations, LPS that wouldn't inflate are now fully expanded, SPS that showed minimal polyp expansion now show very strong expansion and the apical polyps are very extended. Some leather corals that had slimed over and were hunched up are opened up and have looked better than ever. These are corals that have been in the tank for over a year in some instances.
I don't do much husbandry (water changes are once every 6-8 months, I top off RO and attend to dosing solutions at best) so I don't attribute this to a placebo.
I've since removed some rocks and changed the tank around a little so this is no longer a case of only changing one viarable, but for the purposes of experimentation over the past weeks I'd say that corals strongly prefer ammonium compounds over nitrate for growth, and this has rammifications for the reef as a whole in terms of species of algaes etc.
This makes sense as some of the best coral tanks operate a high input high output model to minimise nitrate while increasing feeding, if you break that down to transients, it means these systems are basically geared to produce ammonia and then remove the byproducts from accumulation. This makes sense in the context of wild reefs too - where the majority of food is quickly eaten and subsequently excreted.
To me this echos the frequently repeated 'the best coral food is fish poop' and on a chemical level I'd go as far to say that the best coral food is transient ammonia (ie ammonia that doesn't linger for more than a short time in the water column.
Obviously I'm not commenting on phosphates in this, as the relative ambient concentration of PO4 has many further implications.
The difference between Nitrate and Ammonium fertilisation can be seen in botanical growth quite starkly and I suspect the same is at play here however slightly more complex as we have multiple orders of life (algaes, bacteria and coral) using the same nutrient sources. I've collected this excerpt from
@Hans-Werner some time ago:
I would say I'm absolutely not going back to dosing nitrate and considering I've been experimenting for a dosing system that can provide, with as little interface as possible, all of the corals and inhabitants chemical requirements (including algal growth for food etc) that using ammonium as a cornerstone for this is necessary compared to nitrate.
I have seen my alk drop slightly but I suspect this is from the dosing and not necessarily increased growth, I had higher alk than I'd like due to the nitrate spike previously before this started.
Overall I'm really glad I found this thread, big shout out to
@Randy Holmes-Farley for the idea and also the help in the thread.
