By Bob Goemans
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Bob Goemans corresponds with Ian Beattie

Ian Beattie writes...

Hi Bob

Over the past few weeks I've had problems with some of the corals in my tank. Mushrooms and Xenia are not opening and a Euphyllia coral is dying back. However a Catalaphyllia and a Duncan's coral appear to be OK and are opening out and taking food. I have had all of these corals for several months. I have a 260 litre system with live rock and a refugium containing miracle mud and Caulerpa, which I harvest to keep in check.

Water parameters are checked regularly and are constant around the following values: Ammonia 0; Nitrite 0: Nitrate 10 ppm; Kh 10; Calcium 440 ppm; Salinity 1.025; Phosphate 0.015 ppm; pH 8.0; Magnesium 1400 ppm; and Temperature 26C (79F). Until recently I kept the temperature at 27C but was advised to reduce it towards 25C but I have noticed no alleviation of the problem. Also I had to add an air stone to the system to get the pH to over the 8.0 value - previously it was about 7.8. I also do a water change of 20 litres each week (approximates to 7.7%).

Here is some more info; Lighting: T5s - 2 blue and 2 white for 9 hours each day. Tubes are 7 months old. Water: Changes/movement 11x per hour. Water circulation by Tunze nanostreams 27x per hour. Feeding: TMC Nutra Plus, which contains Artemia, Copepods, Microalgae and Rotifers. It was suggested that, as this is a rich diet, I should reduce the recommended amount by 50%. Also in the past week I have used Phyto Feast rather than Nutra Plus on two days. I only have a nano protein skimmer operating at present but intend to purchase a larger one shortly.

I have 8 fish in the tank, 1 Banggai Cardinalfish, 2 Clownfish, 1 Yellowtail Blue Damsel, 1 Twinspot Hogfish, 1 Cleaner Wrasse, 1 Orangespotted Goby and 1 Onespot Foxface. Also there are 2 Cleaner shrimps, 2 Fire shrimps 3 Emerald crabs and 1 Flame Scallop. The fish do not attack the corals and they are not subject to predation.

Can you give me any assistance with this problem? Many thanks


Ian Beattie

Birmingham, England

Bob replies...

Dear Ian,

Thanks for a well-written letter. Let me first address the feeding regiment, which you only partly address. As for the Duncan/Dendro, its location should be in a shady place where it is fed once every three days. As for the Elegance coral, a low flow area that is moderately lighted and feed only once every two to three weeks.

As for the Euphyllia, it's a low flow species that should be maintained in a low to moderately lighted area. Its polyps, when extended, should 'slowly' move back and forth. I recommend not feeding those in this genus. Water movement more forcible will stop the animal from opening. Mushrooms should also be placed in a similar area, as they prefer very slow flow and low light areas. Of course, mushrooms are not fed. As for Xenia, a moderate flow in moderate light will suffice, however, its clear from your statement that pH went up when adding an aerator, that your aquarium contains too much carbon dioxide, something that drives pH down. When liberated or blown off by using an aerator, pH rises. To correct this situation, you need, as soon as possible, a 'quality' protein skimmer that will oxygenate the bulk water in the aquarium. This increase in oxygen will possibly correct the non-opening Xenia situation.

Hope this helps and keep me posted.



Dear Bob,

After reading your reply I am focusing on the position of the corals in the tank and specifically on the water flow. Have repositioned some to meet the conditions you outline so I will wait and see. Admittedly a more effective protein skimmer would help and I will order one soon.

I really appreciate your very speedy response and your advice.

Kindest regards



Coral Shrinking; Coral Health

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