Corals, strength and Ca/Dkh

puffster · Oct 6, 2017

We all know or hope we as reef keepers know about the positive effects of light and current have on our coral growth. Light is the energy that the zooxanthellae uses to produce the sugar that the coral needs to survive. Current affects coral growth in three main areas of growth; the direction of coral growth, the shape of the of the coral and the strength of the coral. With all this in perspective and in place, is it possible to grow spindly fragile corals with the wrong water chemistry? Also at what points do Calcium and Alkalinity strengthen or hinder the coral growth creating a wimpy or a strong coral colony? I know the "normal" range to keep ( Ca380-400/Dkh7-11) I guess the main question I have, is this: What would be the nominal range of Ca - Dkh does one require as to provide steady strong coral growth opposed to quick growing spindly corals. There is a wide range in the "normal" suggested reef keeping parameters, is there a "sweet" spot for this? I want corals that I NEED the bone cutters to fragg...or a hammer.

Thanks,
Ernie

Randy Holmes-Farley · Oct 7, 2017

I do not actually know if adjusting the water chemistry (say, the alkalinity or pH) can substantially impact the strength of a coral skeleton.

I've seen people speculate that faster growth can lead to weaker corals, but I have never seen any actual evidence, or even a theoretical reason to think it true.

puffster · Oct 8, 2017

Thanks for the info Randy! You never know in this hobby, even when you have been doing it for a while. I guess that I will just add More Flow....see what happens. Happy Reefing!

Dana Riddle · Oct 8, 2017

Anecdotal observations (mine) suggest water motion will make corals grow stronger skeletons, however, this is not always the case. Some Acropora species grow skeletons that are surprisingly weak even in areas of strong surf conditions.

rock_lobster · Oct 8, 2017

I’m not sure that I’ve ever seen a weak spindly sps. Do you have any examples of this?

Dana Riddle · Oct 8, 2017

rock_lobster said:
I’m not sure that I’ve ever seen a weak spindly sps. Do you have any examples of this?

My observations date back to the late 80s/early 90s when we were using powerheads moving 200-300 gallons per hour for water motion. I'm pretty sure I moved my collection of 35mm slides. There might be some examples among those hundreds. I'll look when I get a chance.

rock_lobster · Oct 8, 2017

Dana Riddle said:
My observations date back to the late 80s/early 90s when we were using powerheads moving 200-300 gallons per hour for water motion. I'm pretty sure I moved my collection of 35mm slides. There might be some examples among those hundreds. I'll look when I get a chance.

200-300 gph in a large tank? What is the the gph/g you are referring to.

Dana Riddle · Oct 9, 2017

My tank at the time was a 110 gallon long (72"x18"x19") and the powerheads did not have enclosed motors but were fan-cooled. Naturally, salt would eventually make its way into the windings making them a real safety issue. These were replaced with units that had epoxy-sealed motors, Maxi-Jets, me thinks, four of them, for a total flow of perhaps 1,000-1,200 gallons per hour. And I wondered why I had a lot of detritus. If you were a hobbyist then, at least in the circles I was in, very little was discussed about water motion and the focus was answering all the questions about lighting. This was 1989 if my poor memory serves me.

puffster · Oct 21, 2017

Just asking because in years past, I have had corals that grew as what I thought were growing nice corals but were as frail as rice paper. They were also thin by comparison to what is growing in my tank now, years later. I can't remember tank parameters but I do not want to repeat that cycle of growth. It seemed that the coral was growing at a much rapid pace than normal only allowing the skeleton tissue to produce enough girth to support the colony itself without enough added strength to support any type outside interference. Would be interesting to try to figuring it out. I have some digging and reading to do on coral research results.