Just Guessing

Q. I have a 45-gallon saltwater aquarium with an Amiracle wet-dry filter and a Marineland canister filter. I also have a protein skimmer. First, my live rock is a nice shade of purple and has some mushroom anenomes growing on it. It seems to be slowly dying. All the water chemistry levels are low, and I change 8 gallons of water every two weeks. The saltwater fish are fine. What could be wrong?

Second, I get algae that looks like hair growing on the substrate and on some of the dead corals. This algae seems to grow rapidly for two or three weeks and then die off. Then it starts again a month or two later. Any ideas?

A. Rich, I would love to answer your questions and help you out with your problems, but you have not given much information to go on, so I can only offer you my guesses as to what the problem may be. I'm not sure what you are referring to when you say "it is dying." Do you mean the coralline algae, the mushroom anemones or the life on the rock? I will assume you are talking about the coralline algae.

Coralline algae rely on a variety of factors for growth. Number one is water chemistry — calcium, alkalinity and pH. Because you did not provide me with any of this information I can only speculate as to what may be happening. I suggest checking these levels, particularly the alkalinity, which should be above 8 dKH and preferably closer to 12 dKH. Unless coralline algae have sufficient calcium, bicarbonates and carbonates in the system to calcify, they won't do well.

Other factors include high phosphates that impede the calcification process in coralline algae. Phosphates should be lower than 0.2 parts per million (ppm). Strontium chloride additions also appear beneficial for coralline algae growth.

There are many different species of coralline algae. Some are found in shaded areas, while others thrive in high light levels. However, because you provide no information about your lighting system, I cannot advise you if your lighting is too bright or too dim for the coralline algae to do well.

Your experiences with hair algae indicate that there is a slow buildup of nutrients in the system. The algae will proliferate when these levels have increased to a certain point. Once they have lowered the nutrient level enough, the algae starve and die off. The nutrients then accumulate again and the cycle repeats itself.

Check your top-off water and the water you use for your seawater. Make sure this water is low in phosphate and nitrate. Examine how much you feed your animals, making sure not to overfeed the aquarium. I would also suggest removing the biomedia from your trickle filter. You don't need it and it only contributes nitrates to your system. Investigate how efficient your protein skimmer is and if you can upgrade it to a more efficient model.

Regular readers of this column already know this, but I will repeat it once again — when writing to me with problems, I need as much information as possible about the system and how you maintain it. Without this I am left to second guess what you mean and what may be causing the problems.