There are a couple of simple things you can toggle to encourage faster growth. These points exclude the more subjective, coral specific needs that you have to figure out on your own (par/flow).
1.) Ph. Ph has one of the biggest impacts on reef tanks since there is a lot of carbon in the air surrounding our tanks. Making slow and stable attempts to get ph to 8.3 is not chasing the number, it’s providing a healthy environment for your corals. A ph lower than 8 makes it very difficult for corals to build a skeleton and also makes them more prone to disease. They can extend their polyps and appear fine but won’t give you strong growth. A simple brs study showed that coral growth increased over 50% after getting their ph to 8.3. It’s not hard to do so is definitely the number one thing I’d focus on at your stage. I used to run a co2 scrubber but ended up not requiring it after I employed a fuge and set my dosers schedule to dose everything during the day. This kept ph smack dab at 8.3 all day.
2.) High Alk. This one is more controversial and not as easy. I’ve been utilizing it with great success. I’ve even found it to cause faster growth than a perfect ph. When used in combination with a ph, growth is on a new level. Another simple brs study found 60% faster growth for corals in a 12 dkh setup compared to a standard 8. This is one of those rare occasions where departing from average ocean params may be beneficial. I run a 11.5 dkh tank. The second I increased my dkh from 9 to 11.5, my Alk consumption more than tripled and I started to have noticeable growth every week. This is after getting my ph to 8.3 during photoperiod however.
3.) Higher phosphates. This is one you need to be careful with as there are not only diminishing returns but inverted returns after a point. In terms of area, coral skeletal area growth and polyp extension increase at higher phosphate levels. There is a limit however, namely for sps. At very high levels, the skeleton will grow faster in terms of area but is more porous. This can and will cause the skeleton to break very easily once phosphate levels are too high. I spent a whole year testing coral growth at various phosphate levels and found the sweet spot for optimal growth, density, and health to be between .09-.15.
4.) Feeding. For lps, which I predominantly keep excluding a few free sps, feeding has a huge impact on growth. I’m not talking reef roids either. By far, the fastest growth I’ve seen from feeding comes from large 1mm pellets to all lps that will accept it. This will have a noticeable impact on growth over time.
Hope this helps.
