Mixing Live Rock

Dear Tammy:

Congratulations on your new 85-gallon aquarium!

Yes, as long as you can handle the shipping costs, there is no compelling reason not to mix-and-match different types of live rock in order to obtain a variety of interesting shapes, textures, and encrusting organisms. You’ll want to create aesthetically pleasing rock formations that include caves, arches, and overhanging shelves or ledges and anchor all of the live rock securely in place, and judging from your list, you should certainly have sufficient live rock and enough variety to achieve that goal.

Good circulation and oxygenation of the water is important for seahorses and it’s always a good idea to eliminate dead spots, but I would generally avoid surge devices and wave makers in the seahorse tank. The reason for this is that the stronger the water movement is, the more important it is that the currents be steady and constant in direction. This allows the seahorses to adjust to the current and to find slack-water zones and low flow areas to hold in when they want to move away from the current. There’s too much danger that the seahorses will get blindsided by unpredictable currents or buffeted about by wave makers and surge generators that produce vigorous water movement that comes first from one direction and then from another randomly.

As a guideline, you want your filtration to be turning over the entire volume of the aquarium a MINIMUM of 5 times per hour or your seahorse setup is undercirculated. A waterfall return or spray bar return positioned above the surface of the water to diffuse the outflow will allow you to achieve considerably higher turnover rates without generating too much turbulence or current for seahorses.

Rather than airstones or air pumps, I prefer to use external filters supplemented by small powerheads in my seahorse tanks to create and direct current wherever needed and assure proper circulation without any dead spots. Just be aware that powerheads can become death traps for seahorses if their intakes are not properly shielded or screened off, and take the necessary precautions (Delbeek, Oct. 2001). Carefully conceal the intakes amidst the rockwork where they will be completely inaccessible to seahorses, otherwise shield them, or screen them off with a coarse sponge prefilter.

Best of luck getting your live rock in place and cycling your new aquarium, Tammy! Let us know if you need any directions for cycling it properly.

Happy Trails!
Pete Giwojna