Mixed Bag

[Weatherman]

In January last year, I set up my 120-gallon reef tank from scratch using some of the standard recommended procedures for setting up bare-bottom tanks. This included things like cooking the rock, getting an oversized skimmer, using eductors on the sump return lines and using cuttingboard to cover the bottom. I used kalk to maintain calcium and alkalinity, since the alkalinity demand was so low, and dropped the metal-halide photoperiod down to five hours (I had been running an 8-hour photoperiod on my 180). Since I like Tunze Streams, I added one. Since I’m not particularly fond of UV, I stayed away from adding that.

I’ve always used natural seawater. Alk around 8-9 dKH, calcium around 400 ppm and specific gravity around 1.0255. Never had measurable levels of nitrate or phosphate in any of my tanks. Most of the water changes come from wet skimming (about five gallons a week), but I also swap out a few gallons every weekend when I siphon out the sump, and when I turn the skimmer up real high to remove particulates after blasting the rocks with a maxijet. About once every six months, I perform two 30% water changes in quick succession. Replacement of evaporated water comes from a 5-stage RO/DI unit. Temperature is maintained by evaporative cooling at between 79 and 80F. I almost never use a heater, but I do have a 200W Ebo-Jager, just in case.

My main goal was to set up a nutrient poor environment to keep hard coral. I had done ok with Pocillopora, Pavona, Stylophora, Montipora and Euphyllia for over a year in a tank with a shallow sand bed, but had had limited success with Seriatopora and no success at all with Acros. I wanted to be able to cross over that “Acro barrier”.

It has now been 13 months since I added the first coral to the tank, and I have to admit, I’m not particularly happy with the way things have gone.

On the plus side…
I have no regrets about going without a sand bed. Cuttingboard gets covered in coralline very quickly to give it a mottled appearance, but it’s still very easy to keep clean. I was so happy with the cuttingboard bottom, I removed the sand from my 180 and 155 gallon tanks, and the critters in both those tanks are doing well. Those two tanks have mostly soft coral, anemones, fish, a few Euphyllia, and various urchins, shrimp, snails, starfish and clams.

On the negative side…
Shortly after I moved a big, thriving Montipora digitata from my 180 to my new bare-bottom 120, it died. I never figured out why.

Although I bought astrea snails all in one batch for all three of my tanks, the astreas in my 120 started to get attacked by pyramidellid snails, and were all killed (all 80 of them). Five Mexican Turbos were, also, killed. The astreas and Mexican Turbos in my 180 and 155 were unaffected, and are still going strong.

When new acropora were introduced (I did want to cross the “Acro Barrier” with this tank), they thrived for about three to six months, then suddenly started to fade and were dead within a couple of weeks. Not a tissue-pealing-off the skeleton death, but rather a slow, stop-growing-then-no-polyp-extension-then-get-covered-in-algae death.

After being nuisance algae free for six months, I started to get an outbreak of dictyota and rhodophytes (most likely introduced on a rock a recent coral addition was attached to). There was no competition for space, since all other macros had been killed off during the rock-cooking. The rhodophytes became a plague before they were eradicated by a Virgatus Rabbitfish just a couple of months ago.

Unfortunately, since the rhodophytes were eradicated, things have really started to go down hill.

With the exception of my big, brown Pocillopora, all my other small-polyp hard coral are starting to get pale, bleach, suffer tissue recession and slowly die.

Just out of curiosity, I tested the water for nitrates. They came out at 1 ppm. Not much, but it was very surprising, since I’ve never seen measurable nitrate levels in my reef tanks before. I confirmed the readings with two different test kits (Salifert: ~1 ppm nitrate, La Motte: ~0.25 ppm nitrate-N). What’s even more surprising is that the slightly elevated nitrate is not spurring growth of green algae. I still only have to clean the glass once a week to ten days.

I am very disappointed, and I’m at a complete loss to explain any of it.

I use the same fresh and salt water for all my tanks. All my fish are fed the same food. But something is killing the hard coral in my 120, and I don’t know what it is. I’ve done the obvious things like running carbon and performing water changes, and it has had no effect. I even swapped out my year-old metal-halide bulbs. No change.

I am so envious of people who can keep acros without much difficulty. Even after 33 years, I don't seem to have mastered the skills required.

[Graham]

That's a drag, Weatherman... Are you sure it's not "something in the water"? I know zero about collecting NSW, but is there any way that could be the culprit? Have you only had problems with Acros since going BB?

[Weatherman]

That’s possible.

One could argue that all my other critters are ok simply because they are more tolerant of some toxin in the water.

I used to get the NSW from a couple of lfs in the area. They get the water from two, main distributors. The distributors collect the water from Government Cut (Miami Harbor Entrance), and then filter it and sterilize it. For the past four months, I’ve taken home delivery of the water from one of those distributors.

I’ve never considered the use of NSW a negative, but maybe it is. At a minimum I'm going to stop the home delivery and go back to getting NSW from the lfs again. If that doesn't stem the tide of decline, I may try going back to using ASW, like Instant Ocean. I used IO in my tanks before I moved to Florida.

I’ve never had any success with Acros before going bare-bottom, so to get three to six months of good growth before the coral starts to decline is a step forward. But, I hate seeing anything in my care die.

I’m still missing something. I was hoping the removal of the sand bed was the key, but it must be something else.

[Graham]

Originally Posted by Weatherman

That’s possible.

One could argue that all my other critters are ok simply because they are more tolerant of some toxin in the water.

I used to get the NSW from a couple of lfs in the area. They get the water from two, main distributors. The distributors collect the water from Government Cut (Miami Harbor Entrance), and then filter it and sterilize it. For the past four months, I’ve taken home delivery of the water from one of those distributors.

I’ve never considered the use of NSW a negative, but maybe it is. At a minimum I'm going to stop the home delivery and go back to getting NSW from the lfs again. If that doesn't stem the tide of decline, I may try going back to using ASW, like Instant Ocean. I used IO in my tanks before I moved to Florida.

I’ve never had any success with Acros before going bare-bottom, so to get three to six months of good growth before the coral starts to decline is a step forward. But, I hate seeing anything in my care die.

I’m still missing something. I was hoping the removal of the sand bed was the key, but it must be something else.

Yes. Weird, since I'd think NSW is exactly what they'd want.

With so many reefers keeping Acros in particular long-term regardless of sandbed or not, I don't think that's the main factor either - as you said.

Hard to say - did you keep Acros back when you used IO?

There's something going on....no reason you shouldn't be able to keep them. I assume your Acros come from multiple sources?

How about your plumbing or other hardware that comes into contact with the water. Is there anything metal anywhere? Was the tank ever treated with copper? You don't have any Acro flatworms or anything, do you?

[Weatherman]

My experience with keeping small-polyp stony coral is limited to just the past 2 ½ years (in fact, the first sps I ever bought, I still have). So it’s exclusively NSW for them. Before that I kept only fish, soft coral and various inverts.

Acros have come from three different stores in the local area. About 50% frag resells and 50% new wild caught.

Plumbing setup on my tank is very simple. Iwaki 55 driving the sump return and eductors. Iwaki 40 driving the skimmer. All rigid and flexible PVC. My other two tanks use the same type of plumbing. I haven’t taken either of the Iwakis apart to check for rust or corrosion. But, I can add that to my list of to-do’s.

I haven’t used any meds on my tanks since 1978, and then only on the tanks with fish only.

The reason why this is so frustrating is that I’ve been in the hobby so long that I know how to avoid all the major bugaboos. I was thinking that the cuttingboard was leaching toxins into the water, but I have baby Pocillopora growing directly on the board. I can’t imagine they would survive in direct contact with something toxic.

One other thought is that the 55-gallon water barrels I’ve been using to store NSW are releasing some toxin. They shouldn’t. I checked back with the company I bought the barrels from and they are food safe and have not had any anti-mildew applications. But I’m going to stop the bulk water deliveries for a while to eliminate that possibility.

Another thing I’ve thought about is toxins in the tap water. But I use a 5-stage RO/DI unit and I’ve been replacing filters cartridges very frequently. If I ever see TDS above zero, I either replace the DI cartridge, or, if it has been more than six months, I replace all the other filters.

I have taken many closeup pictures of my acros. Unless they hide extremely well, I haven't seen any parasites.

[redwinger]

I would have to point my finger at one of few things. The water you are getting, parasites (AEFW, red bugs etc.) or you are having some abrubt changes in water chemistry. Nitrates are not un-normally high IMO and you seem to have the other bases covered. Did you buy this tank new or used? If used, the previous owner might have used some meds on it that you are not aware of. If you purchased it brand new then you would know the complete history of it.

[Weatherman]

I bought the tank brand new.

Water chemistry changes are an unlikely cause of the problem. I’ve long gotten into the habit of checking my alk and specific gravity twice a week. I very rarely make adjustments, but I like to check things out just to make sure they are both in line.

Since, with the exception of the 30% swaps I make twice a year, I replace about ¾ of a gallon a day for the skimmate and two to three gallons on weekends for sump cleanup, any effect from water changes will be, in most cases, very slow.

One of the more interesting proposals, that was suggested to me, is that this coral is somehow responsible:




This is my big, brown Pocillopora; the first sps I bought; the coral I’ve had for 2 ½ years.

It has already demonstrated the ability to spread polyps all over the tank. I have about 45 little, brown Pocillopora colonies sprouting up everywhere. The theory is that when this coral goes on a polyp-spreading spree it’s killing other coral in the tank. It’s an interesting idea. The Pocillopora is, by far, my most healthy coral.

[Weatherman]

Whenever I think water quality is an issue, I take a look at some of the littlest coral colonies in the tank.

Like this one… Here it was eight months ago:




Same colony, a couple days ago:




A tip broke off my Seriatopora a couple months ago, so I put the frag up in a rock crevice. This is what it looks like, today:




The tissue recession and bleaching is not affecting the little polyp castoffs and frags. It’s just affecting the larger colonies, and any newcomers I add to the tank.

[Weatherman]

Maybe I should throw a couple questions out there for successful Acropora keepers…


When you first started trying to keep Acropora, were you immediately successful, or did you encounter problems?

If you did encounter problems, what were they, and were you able to pinpoint the exact cause?

[Mike O'Brien]

I had success right away in my high nutrient DSB tank that was overgrown with caulerpa, and had a crappy skimmer. After a year or so with sps I figured I'd try BB so I could get the clean water they needed. In the beginning I ended up losing some of my largest colonies that were grown in my last tank, luckily I was able to save frag's in another tank. What it came down to for me was starving the coral's. I started feeding extra heavy and adding AA's, thing's started to improve, I added a ball of chaeto and thing's improved more. Finally I did the unthinkable and added 6" of sand to the setteling area of my sump. What I think this add's to the tank is actually stability, for one more stable nutrient's for the coral's, another and most will find it hard to believe, but for me it has provided more stable calcium and alkalinity. I unlike alot of other's had a hard time maintaining calcium and alkalinity especially when my coral's were growing in the full BB. Now it's still tough, but not as bad. I'm adding a calcium reactor this wednesday to end my struggle. All I can say now is that every coral in my tank is healthy and growing. I still feel I benefit alot from no sand in the tank and the great flow I have, and if I ever have a problem with the sand i can remove it without disturbing my tank. What it comes down to for me is just being able to watch the coral's grow. Sps are pretty boring if they are not growing. I gave it my best, but for the sake of the tank that's what I did.

[bap]

I'm wondering if the nuisance algae is symptom of the real problem. In my tank I have no hair algae but I recently had an outbreak of bubble algae.

I have decent flow in my tank, about 50X. Then I noticed a little recession on a couple of colonies. I had also noticed my ORP had gone down to ~340 from ~380, but I thought that was just from not cleaning the probe.

Well, when the recession started I put 2+2 together and thought phosphates. I measured and got 0 phosphates, 0 nitrates. The recession got a little worse and looked hard for detritus and found nothing and the rocks looked clean. I took a turkey baster and found out the rocks were far from clean.

I basted every day for a week and the ORP went back to ~380 and the recession stopped.

Is there anywhere detritus could be hiding?

[Weatherman]

Mike,

That does seem to be a recurring theme for new bare-bottom tank keepers. We just don’t give our coral enough to eat, so they do ok for a while, but then they literally starve to death.

It’s always tough to keep food plentiful and keep dissolved nutrients (such as phosphates), low. But, now that we have powerful skimmers and strong flow in our tanks to remove uneaten food quickly, we probably need to be much more aggressive in feeding our tanks.

Good point: Provide more food!

[redwinger]

Bap, detritus could be hiding under the starboard but you would have higher than normal nitrate levels if that was the case. Phosphates tests are pretty useless unless you have a clorimeter(sp). Weatherman when you get the recession is it from the base up?

[Weatherman]

Originally Posted by bap

I basted every day for a week and the ORP went back to ~380 and the recession stopped.

Is there anywhere detritus could be hiding?

That's another good point: Give rock a good blasting on a fairly frequent basis to losen up detritus!


(fortunately, I do that already)


redwinger,

When my acros die, they just simply stop growing, then stop extending their polyps, then slowly get covered with patches of little strands of algae. No top-down or base-up tissue loss. When the colony dies, the whole thing dies.

[Mike O'Brien]

I never had the mean's to test it myself then, but what is you're ph range during the night ? Now that i have a monitor I have 8 in the morning and up to 8.15 or so. This is with kalk drip and lit chaeto 24/7. I think the massive flow we use can keep the ph from getting too high, but maybe it can also it to get too low at night.