Top 10 Reasons Your Corals Are Not Growing and How to Fix Them!
1) Stability Is King - Stop Fussing With It
Corals are highly adaptable and just need you to keep the environment stable. Many hobbyists experience slow coral growth simply because of this instability. Even the slightest change in pH, temperature, salinity, calcium, alkalinity, nutrient levels, PAR levels, light spectrum, or water flow can throw off that stability that corals need. So the advice here is to stop making regular changes to these things and just let the tank stabilize.
2) Set Your Lighting Once And Forget It
You don't need to adjust your lighting, ever. After setting the spectrum, creating a schedule, and testing the PAR levels upon initial light setup, you should never change or adjust your aquarium light again. Even small changes to the PAR, spectrum, and photoperiod in your aquarium will stress out the coral and slow them down.
3) Maintain Alkalinity - Shoot for 9.0 dKH
Corals are sensitive to changes in alkalinity levels and it just so happens that alkalinity is depleted relatively quickly in a reef aquarium. Likely the reason that so many hobbyists struggle with maintaining a stable alkalinity level. Take the necessary steps to dial-in dosing methods that will maintain your tank's alkalinity as close to 9.0 dKH as possible at all times.
Don't ignore alkalinity this week and then pay attention to it next week. Pay attention to alkalinity at all times and don't let it budge out of range. If you encounter a swing, fix it immediately, and monitor the tank's levels closely until stability is maintained. Yes, that means you might have to test your tank's alkalinity level daily, and be sure to use a reliable alkalinity test kit so you can be confident you're getting consistent results.
4) Stable Calcium and Magnesium Levels Are Important Too
It might seem redundant at this point but stability really is the ticket. Calcium and Magnesium are super important for the coral's health and although these parameters are not as volatile as alkalinity, you still need to maintain rock-solid levels for the corals to grow optimally.
Shoot for 440 ppm of calcium and 1350 ppm of magnesium and don't let it stray. Small changes to these parameters will affect your coral's ability to grow and supplying stability on all fronts is going to give you the best results. Reliable test kits are as equally important as performing the tests regularly.
5) Fix Your pH
While a reef tank can survive with a pH as low as 7.8, raising that pH as close to 8.3 as possible will exponentially increase coral growth. Corals grow slower in lower pH water, it's a fact as proven by science and BRStv alike! In fact, you can achieve up to 50% more coral growth with a corrected pH. Even just raising 0.01 - 0.02 pH points will help and the closer you get to 8.3, the better your results will be.
The good news, we know exactly why pH suffers in aquariums and there are very clear-cut methods for improving it. All you have to do is take the time to monitor your tank and fix the problem.
Learn More With BRStv: Top 5 Tips For Raising pH In Your Reef Tank
6) Feed Your Corals
Corals benefit naturally from capturing prey and acquiring dissolved nutrients from the water. In a reef tank, most of your coral foods like Reef Chili and liquid plankton additives are replicating prey and providing nutrients the coral cannot easily acquire any other way resulting in faster growth. Dosing amino acids also helps corals create tissue faster which is exactly why you see better growth and coloration when target dosing amino acids.
Don't neglect to feed your corals regularly and dose amino acids if you want to see better growth!
7) Avoid Running With Zero Nitrates and Zero Phosphates
If you're running a tank with undetectable levels of nitrates and phosphates for an extended period of time, you may be limiting coral growth. While advice from days past may have blindly directed you into running extremely low or undetectable nitrate and phosphate levels, this may result in starving your corals let alone make way for pesky organisms like cyanobacteria and dinoflagellates to grow. Minor levels of nitrate and phosphate in the water are a good indication your corals are getting the nutrients they need to grow optimally.
8) Eliminate Dead Spots In The Water Flow
Corals need flow to acquire food and expel waste. This is critical to their health and if you have dead spots or areas of low flow in the tank, you could probably get better results by supplying better flow to those areas. If you find corals are just not growing all that well in certain areas, its likely flow in those areas is your problem.
9) Remove Contaminants or Irritants From The Water
Sometimes running a little carbon or doing more frequent water changes will remove irritants from the water that are stressing your coral out.
10) ICP For The Unexplainable
If you are stumped and just cannot figure out the problem in your tank, mailing out a sample of your aquarium water for ICP analysis should help you figure it out. There are a variety of things that could potentially be affecting corals negatively that we don't actively monitor as hobbyists and an ICP test should pick those things up and help you formulate a game plan.