Water quality is of course measured, and for both types of aquarium the four basics are the same – ammonia, nitrite, nitrate and pH. With the reef the list is extended, taking into account for example alkalinity, calcium, magnesium etc.
Water quality is more than measurement however. Though a personal thing, I count water movement as part of quality. Water movement brings oxygen and food to corals, and helps removes dirt and mucus from them. It ensures fish have sufficient oxygen, and also makes them feel more ‘at home.‘ It also oxygenates a reef and assists in keeping it clean. The seawater is ‘clean’ and freshened in all parts of the aquarium. With good water movement the very important gas exchange is achieved – water is continually delivered to the surface to re-oxygenate.
Plenty has been written on this subject, and on this website, already about water movement and its creation. The methods are generally straightforward.
However, I suspect that many aquarists, particularly newcomers, look at water movement as circles. There’s the aquarium, and the guideline suggests water movement of, say, 10x the net gallonage per hour. Easy! Get a couple of powerheads which pump that amount of water, or somewhere near, and the job is done.
If suggestions have been understood, the powerheads are placed strategically to create chaotic and random water movement. Still well and good.
It is thinking ‘in circles’ though. Perhaps it would be better to say thinking ‘horizontally.’ No matter how carefully the powerheads have been placed the seawater cannot possibly reach all parts of the aquarium with good movement. All aquariums have quiet areas where corals that prefer calm can dwell.
So the aquarium is equipped with what seems to be sufficient power to move the water. Probably it is.
What about the ‘vertical’? No, I don’t actually mean pump water vertically in the aquarium, I mean deliver water low down from higher up. What about one additional powerhead that is in an accessible position but pumps water through a tube to, say, a spray bar behind the lower reef or even under it. There are different ways of delivery. All the powerhead needs is a sleeve on the intake (sponge or similar) to stop debris and that’s it. Maybe two powerheads would be required. Whatever.
The aquarist can then be more sure that water quality is high everywhere, with the benefits that can bring.
Advanced systems can use carefully designed closed loops, where the water outlets are positioned in strategic places to ensure fully advantageous delivery. The ‘ordinary’ aquarist need not go to these lengths unless really desired. The use of additional water movement devices, one or maybe two, will do a fairly similar job at a very reasonable cost.