Q. I have a 30-gallon (tall) saltwater tank. Lighting consists of two 50/50 15-watt tubes in a dual fixture. I have about 30 to 35 pounds of live rock in the tank, and water circulation is controlled by one 402 Hagen powerhead. I'm also currently running a Visi-jet protein skimmer. The tank is home to one tomato invertebrate, one "percula" and one tomato clownfish.

My question is this: I've tried to revive my live rock by adding SeaChem's Reef Builder product to the aquarium at water changes (done monthly and changing about 5 to 7 gallons of water), but the red coralline algae never returns — the rock almost looks like base rock now. My tomato invertebrate is now white after a very warm summer (without a chiller), and even though it is now winter it has not regained its former color, and has not fully extended since. The pH is at 8.3, salinity is 1.024, and phosphates are between 0.5 and 0.8 ppm.

A. I think one of the answers to your problem lies in the phosphate level. A reading of 0.5 to 0.8 ppm (parts per million) is five to eight times higher than it should be. Coralline algae require calcium and carbonates in the water in order to calcify and grow. High levels of phosphate interfere with this process, and the coralline algae will cease to grow and will eventually die off.

Adding Reef Builder as you do, I suspect the alkalinity and calcium levels are too low. Adding this supplement only once a month is probably not adequate to maintain high enough calcium and alkalinity values. I strongly recommend that you purchase both alkalinity and calcium test kits so that you can find out what levels you have, and then use the Reef Builder product to raise and maintain them.

In the long run, however, I think you would be better off using one of the calcium hydroxide (kalkwasser) products available to maintain these parameters. The high pH of a kalkwasser solution will help to lower the phosphate level by binding with it, causing it to drop out of solution, while boosting calcium and alkalinity. I would also recommend upgrading your protein skimmer to a larger, more efficient, design, which will also help lower phosphates.

Although you do not mention if you have any substrate in the tank, I would recommend that you add a 1- to 2-inch layer of a fine grade of aragonite sand. This material will also help maintain calcium and alkalinity. You didn't note the source of the freshwater you use for water changes or evaporation top-offs. Check your freshwater source for phosphates. A recent federal mandate states that municipal water suppliers must add phosphate to their water to combat the dissolution of lead in the water pipes of older homes. This may be a source of phosphate in your tank.

Finally, you do not mention if you add any strontium to your aquarium. Strontium is a useful element for coralline algae, and they tend to grow better when it is added.

Much of what I've written above also applies to why your "tomato invertebrate" is not doing well. Although I don't pretend to know what a "tomato invertebrate" is, I will hazard a guess that it is some sort of anemone or coral. In either case the reason it is turning white and not extending as much is that the light level is inadequate. Two 15-watt lamps on a 30-gallon tall is simply not enough to keep any light-dependent invertebrate in good health, and may be another factor as to why your corallines have disappeared. You need at least four regular output fluorescent tubes or two very high outputtubes over the tank.

So Much Filtration
Q. I've recently seen numerous ads for "algae scrubbers" claiming they are the only "natural" filters on the market. Is this true? Are there any other less expensive filters just as good for reef tanks? I currently run two Biowheel 300s (four wheels), a Sea Storm 240 and a Sea Clone protein skimmer on a 55-gallon reef setup. Should I get rid of all these and replace them with a scrubber?

My tank holds 13 pounds of live rock, 25 pounds of seven-month old base rock, four anemones, open brain coral, thriving mushroom anemones, seven shrimp, a sebae clown, a coral beauty, and 11 Turbo snails. Everything seems fine: nitrate is 20 ppm, there is no nitrite, no ammonia, pH is 8.5, calcium is 425 ppm and phosphate is 0.8 ppm. Will an algae scrubber give me even better results? Will I be able to add more fish because of these results?

I've tried making home-made scrubbers, but only get red slime algae no matter how much or what type of light I use. My lighting consists of two Trichromatic 40-watt tubes (on for 10 hours a day), two 40-watt actinic tubes (on for 10 hours a day), and one 20-watt blue moonlight tube (on for 24 hours). Is this sufficient? Should I add more?

A. My feelings and views on algae scrubbers can be found in the book I co-authored with Julian Sprung (The Reef Aquarium, Volume One, 1994), as well as in an article I wrote in the Aquarium USA 1998 annual. I have also been seeing the various ads in the national magazines touting algae scrubbers and the wonders they can produce, I have read a few articles recently published in the scientific literature and elsewhere, and I have continued my discussions with some of the scientists who use this technology. I will, however, save my comments for a separate column.

Suffice it to say the main problem you are having with your aquarium can be traced to the same one cited in the previous letter — namely, the phosphates are very high! I know from another letter you sent me that you were having massive algae problems until you added your 11 Turbo snails. You need to ascertain where all that phosphate is coming from and deal with it. (See my reply to the previous letter for some ideas on possible sources and how to deal with them.)

I am a little puzzled, though, by your filtration system. With all the live rock you have in the system and only two fish, I don't understand why you have four biowheels and a fluidized bed filter on a 55-gallon aquarium. To me this sounds excessive, and may be another reason for the unwanted algae growth and high phosphates. If you were to remove these filters and upgrade your protein skimmer you would be a long way toward dealing with the algae problem, the high phosphates and even reducing the nitrates. Yes, an algae scrubber can do much the same, but as you have observed already, they are not easy to set up without seeding them with the proper algal cultures to begin with. As noted above, I will discuss algae scrubber filtration in more detail in a separate column.