By Bob Goemans
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Bob Goemans corresponds with Borris Yelts

Borris Yelts writes...

Hi Bob,

Have you ever used the sun to grow corals in captivity? I have set-up a greenhouse type system in April of last year in the UK and so far everything I have in sunlight is growing at rates I have never before seen. I grow almost all types of coral but have yet to try intense light loving Acropora. Presently have around eight types of Acropora of the easier types in terms of care that are doing extremely well.

What are your thoughts on this method and would you think any Acropora species would be able to live and grow in the sun here in the UK?

My system is not to make money, as it's more of a passion that by doing this it helps the corals in the wild. My system holds 6500liters of water and presently has over 500 corals in it and growing out. I do not use skimmers just DSB and live rock. I also grow my own phytoplankton and produce my own live rock to sell locally at extremely low prices so I can afford to keep this project going. I have had the best growth with Montipora, (the stuff grows like weeds in the sun!) as the frags I started with are now the size of dinner plates! I also have acans, hammers, mushrooms, various sps and clams and they all are doing great.

As of now, everything I have is going good and have also noticed over the many past months of using sunlight that corals recover from any types of damage very fast. I even find that the sun seems to help clean the water, as it remains crystal clear.

Again, what about the more light loving Acropora, as they may be more difficult to keep healthy?

Borris Yelts

Preston, UK

Bob replies...

Hi Borris,

Thanks for your email and as to your questions, I've had some past reef aquariums somewhat situated so sunlight would enter during morning hours. Most stony corals and some other species, including clams that were in those actual sunlit areas responded exceeding well! However, I live in the southwest portion of the USA and learned quite quickly with these type systems that any lengthy sunlit timeframe would raise water temperature where my chiller would sometimes even operate during our cooler months. Nevertheless, did notice increased growth and coloration on some species during the timeframes where sunlight actually lit these species. However, these periods/length of time actually lit by sunlight changed from season to season, and I could actually see the difference in growth rates and coloration between seasons - summer verses winter seasons. Besides the sunlit timeframes changing from season to season, temperature fluctuations, and algae growth in the sunlit areas of the aquarium were two additional factors that concerned me the most during these 'experiments!' In fact, unwanted algae growths often became a hassle in those sunlit areas, as it seemed to prefer the sunlit areas, including the substrate areas next to the aquarium side panels to other areas in the aquarium, and always added more time to my regular cleaning timeframes to keep in under control.

Even though the 'sunlight' aspect was an interesting experiment/timeframe, got away from placing aquariums where sunlight would shine into the aquarium over the past decade as lighting equipment has made leaps forward. In fact, lighting improvements have now made it possible to accomplish everything I want to in an 'aquarium,' especially LED equipped systems. And since my goals are simply well-balanced environments, and not a money-making frags for sale type systems, have more 'light' control now by using LED equipped fixtures to light my aquariums, which are not only lamp maintenance free, but power-wise inexpensive to operate.

As to the availability of sunlight in some parts of the UK, during my speaking engagement in London several years ago, rarely got to see the sun! But if sufficient in your area, sunlight will no doubt help promote more growth 'if' the surrounding water parameters are similar to natural seawater, e.g., calcium, alkalinity, and magnesium are in a balanced state.

Of course, hammers and mushrooms are low to moderate light/low current flow animals, whereas many Montipora species especially like intense light and swift water movement. As to Acropora, there are various species that do well in moderated light, whereas other species need intense light and very good water movement to remain healthy and colorful. And would think from what I can gather from your letter, you have a situation that is going to require a 'give and take' effort as to what species works well and where to place them in your system(s). Yet keep in mind, many corals are mostly photoadaptive, therefore they may/will adjust to various lighting intensity/photoperiods, and if not sufficient, may lose some of their coloration or become bleached out. And if feasible, maybe you could utilize LED lamps to get by on cloudy days or supplement just the coral species needing more intense illumination.

In fact, I've visited home systems set up in outside yards in southern California that were quite successful. Therefore, depending upon species and the amount of useable spectrum and intensity/useful timeframes, and temperature control, an outside greenhouse coral farm is a great 'adventure,' and one worth experimenting with.

As to no skimmer, find that interesting, as I'm a great proponent of their use, however, always say, if it ain't broke, don't fix it! So, if you're having good success, keep going that direction.

And must say, my Monitpora's are doing very good under my LED lamps, as one, red with blue polyps, continues to grow very nicely! (Monitpora - my favorite stony!)

Good luck with your system, and if you have any further questions or comments, please send them my way.




Sunlight; Lighting; Corals

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