Reef Matters

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jhnrb

Reef enthusiast
Seemingly Contradictory Advice on Reef Matters

QUESTION:

I have been reading a lot lately, books and some articles on the Web sites, and I was wondering if you could clarify for me some points I've come across that seem a bit confusing; it may be due to the fact that many of the articles were written long ago and maybe become outdated, but there are a number of statements that seem almost contradictory about the following issues:

dKH: What is the optimum value for a reef tank? I've read, depending on the >sources: 10-11 if using limewater, 15-18 if not. 7-8 in order to keep a high calcium level in the tank. 15 in any case. I have a low dKH value in my tank (6-7); I use a kalkreactor, my ph is stable (8.2-8.4) and my calcium level is 480. Is that OK?

Macroalgae: On one hand I've read they are very beneficial since they help to keep down nitrates and other pollutants, and on the other that they may be even harmful to corals. I have several species of Caulerpa, Ulva and Halimeda that grew in the tank by themselves (I haven't introduced them); I cut them regularly so they don't overgrow the corals, but should I try to eliminate them completely? They look so nice...

Water changes: For years i've believed that an amount of 20% a month (5% weekly) was the right thing, but recently I read an article of German practices that 5% monthly was enough. Is it really? I have a tendency to change a lot of water since it's the only way to remove detritus and other unsightly dirt from the tank.

I recently started reducing my water changes since a friend suggested that it's better to let it "stabilize", but then hair algae started to grow.

ANSWER:

When reading a lot and when reading material that is new and material that is old, one can come accross statements that seem contradictory especially if taken out of context.

1. dKH - alkalinity - buffer

-If the hobbyist does not use limewater : dkH of 15 to 18
-If the hobbyist uses some limewater but not a lot dKH of around 12
-In fish aquariums dKH of 12
-In reef aquariums where all evaporated water is replaced by KW dkH of 7 or
8.
-A dKH of 6 or 7 is still fine providing your pH does not fall below 8.2 in the
AM.
-Lately, since most hobbyists replace all evaporated water with limewater
what I would suggest is a dKH of around 7 or 8 as the norm

2. Calcium is usually recommended by most authors to keep Ca++ levels around 420 to 450 ppm. 480 is a little high but not dangerous. I would not increase it any further though. Ideally let it fall a little. Of course one should take into consideration that calcium demand varies and that it is important to keep track of calcium levels regularly so they do not start to vary widely from one day to another due to increased demand by corals and coralline algae.

3. Macro-Algae are ok as long as you trim them from time to time so they do not overgrow corals and rock formations. Also the most important thing to watch for is sudden die-offs which usually occur when the pH is suddenly changed. This can happen when you perform a water change and do not pay attention to the pH of the water you are adding. It should be about the same, ideally the same, as the one in the main tank.

The ones mentioned in the question above are good ones if you want to keep them growing. Adding a little iron to the tank makes that easier and will enhance the color to a deeper green, but, be careful with the amount of iron used. Too much could have adverse effects (algae blooms)

Light is an important factor here too as to grow they need energy and they get the energy for photosynthesis from the light. Trim algae back from time to time and do so knowing that after you do the trimming, running some carbon for a few hours maybe a good idea in case some toxins leach in the water.

4. Water changes The trend seems to be to reduce them to keep the water more stable but only in aquariums that use live sand and live rock. The 5 percent indicated per month seems just fine although some do not even perform that much. Those who have a lot of live sand and a lot of live rock change a max of 5 percent per month. Those who use different filtration types are doing larger changes but doing them more frequently. 3 % to 5 % a week seems like a good average to recommend.

With regard to the detritus: siphon it out. That is what most hobbyists do. Mechanical filters are used less and less.
 
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