Water changes, Skimmer and LR

I have never vacuumed my substrate in my SW tanks. I have also used plain old pool filter sand for the last 6 years as well since we made the move from Michigan to Louisiana. I have had GREAT luck with the stuff. I was doubtful but after the move I was strapped for cash and just went for it.

 

My DSB in the display is silica play sand and works great. 6 years now and full of life. Despite all the warnings about silica sand in a reef, I've never encountered a problem. Got all of my flow directed at the rocks and corals, so I don't get sand blowing around. This play sand is very fine grained, and rounded in nature which things love to move around in. However I have no large animals (sand sifting stars or gobies) to dig too much. I think these would cause me a major problem by de-stabilising rocks, eating the micro life and burying particulates.

 

I have bought nothing since I discovered it. I have not had any issues at all either. I just rinse it as Bud says. I put it in a 5G bucket about 3/4 full and put hose all the way to the bottom and let the water flow as I stir it. Then I dump it onto an old bed sheet for another quick rinse.

 

Sabbath - with regard to your use of the skimmer, i have found an article from Randy Holmes Farley,http://www.reefkeeping.com/issues/2004-10/rhf/index.php an excerpt from which reads;

Negative Effects of DOM: Energy and Nutrients

The same effect of providing energy and nutrients to organisms that may be considered a benefit when the organism is something that aquarists prefer to thrive, might well be considered a detriment when the organisms in question are cyanobacteria or microalgae. Aquarist preferences aside, however, organic materials can provide such "benefits" to organisms whether they are preferred or not.

Not only can DOM be taken up directly to provide carbon, nitrogen, and phosphorus, but it can be broken down by organisms and released as inorganic nutrients, such as orthophosphate, ammonia, nitrite, and nitrate: 16

(CH2O)106(NH3)16(H3PO4) + 138 O2 � 106 CO2 + 122 H2O + 19 H+ + PO4--- + 16 NO3-

organic + oxygen � carbon dioxide + water + hydrogen ion + phosphate + nitrate

These inorganic nutrients can then drive the growth of undesirable aquarium algae aquaria, and can cause other problems (such as phosphate inhibiting calcification by corals). Consequently, DOM (and also POM) can act both directly as a nutrient source, and also as a source of inorganic nutrients.

Some aquaria have large growths of cyanobacteria or microalgae, and in these cases exporting some of the DOM and POM from the water column may be beneficial in reducing the problem. The addition of vinegar to limewater has been correlated with the growth of what appear to be bacterial mats in some aquaria. Presumably, the bacteria thrive on the acetate provided by the vinegar.

Negative Effects of DOM: Oxygen Levels

Another drawback to organics that are taken up by bacteria and other organisms is that in order to metabolize them, such organisms use oxygen (if they are aerobic organisms). Equation 1 (above) shows the net effect of what happens when organics are metabolized. For each carbon atom in a typical organic molecule in seawater, 1.3 oxygen molecules are consumed. At levels of DOM in natural seawater, on the order of 1 ppm, this result implies that oxygen would drop by 3.5 ppm if it were all fully oxidized. Obviously, not all of the carbon will be rapidly and completely oxidized, but if organic levels are appreciably higher in some aquaria than in the ocean, then the oxygen depletion potential may be very important relative to normal saturation levels on the order of 7 ppm oxygen.

The consequence of this oxygen consumption is that oxygen levels may be lower in aquaria with high organic levels, especially at night when photosynthesis is not producing excess oxygen. Moreover, during a power failure when both aeration and photosynthesis are greatly reduced, the metabolism of organics proceeds merrily along, reducing the oxygen content of the water faster than it would in the absence of DOM.

Negative Effects of DOM: ORP

Many aquarists attribute low ORP readings to elevated DOM (and POM) levels in aquaria. That is likely true in many cases. However, the drawbacks of lower ORP that many aquarists fear may well be caused directly by the organics themselves, rather than by the ORP. So it may, in effect, be double counting to claim that high DOM is undesirable purely because it causes lower ORP. In a previous article I argued that ORP itself, especially when being perturbed with an oxidizer such as ozone, is not a good indicator of water quality generally, or organics in the water specifically. Nevertheless, there is a strong connection between organics in the water and ORP that aquarists should be aware of. Exactly how they are related in reef aquaria is complicated and not all aspects are well known, but what is known is described in the article linked above in both easy to understand and also in more rigorously scientific discussions.

Negative Effects of DOM: Toxins

Marine organisms can produce a multitude of organic toxins. It is beyond the scope of this article to go into the many toxins that might concern aquarists, but some discussion is certainly merited. These toxins may be intentionally released by organisms to kill neighbors or competitors, or they may be kept internally to ward off predators (being released only during predatory encounters which may or may not end in death). Some are fairly simple biochemicals. Domoic acid, for example (Figure 2), is a fairly simple biochemical that is produced by many species of diatoms. Ciguatoxin, on the other hand (Figure 3), is a complicated molecule made by a dinoflagellate. As it works its way up through the food chain to people, it has been implicated in many fatalities and is reported to sicken 20,000 people per year.20


Figure 2. Domoic acid, a toxin produced by diatoms.


Figure 3. Ciguatoxin, a toxin produced by dinoflagellates.
Caulerpin (Figure 4) and caulerpicin are sometimes referred to as toxins, although they appear to be primarily growth regulators present in various species of macroalgae, especially Caulerpa. They are not particularly toxic to animals or bacteria in most studies.4-10 Many aquarists decline to keep Caulerpa sp. in their aquaria, sometimes citing the possibility of elevated levels of such toxins as a reason. Whether these particular "toxins" are of primary concern or not, looking at the structures of these sorts of toxins can help suggest ways to remove them (carbon, for example, since they are very hydrophobic), but I have never seen measurements of the levels of any toxins in aquaria, or comparisons of how well different export mechanisms might reduce those levels. I would consider such measurements to be of significant value to aquarists.


Figure 4. Caulerpin, a compound produced by macroalgae, including Caulerpa species.
Negative Effects of DOM: Light Absorption

One concern with DOM is that it can absorb light. That absorption serves to decrease the intensity of light reaching photosynthetic organisms, and can also yellow the aquarium's water. The use of activated carbon to remove the yellow coloration in aquaria by binding organic materials has been addressed in a previous article. Other organic export and degradation methods can also serve to reduce light absorption and coloration, including skimming, ozone and other oxidizers, and the use of organic resins such as the Poly-filter.

 

As algae is producing amino acids and sugars constantly, while you perceive a nutrient related problem (cyano, dinos) it's probably best to run the skimmer 24/7. Then to aerate the water generally (ie increase oxygen in dark, and prevent pH increase in the light) you could try the "bubbles on a screen thing" as this does a similar job but don't skim anything out the water, if that's your preference. Someone will probably explain that cyano and dino's will die without nutrients (running a strong scrubber) and that you dont need to run a skimmer but this theory is flawed in my opinion because the stronger the scrubber growth, the more amino acids and sugars are produced, thus providing more than enough nutrients for pest growth (unless it's removed). Hope this helps.

 

Garf are these aminos and sugars coral food?

 

Yes and food for lots of other things.

 

Not sure it does Floyd as strong scrubber growth implies there's plenty of nutrients for photosynthesis. It may be an Allelopathic effect, but evidence for this is sparse and very hit and miss as to the effects Allelopathy has, sometimes a benefit, sometimes not, depending on the actual algal strain on the screen, and the particular Allelopathic compounds involved. Not surprised if this sounds a bit far fetched but even professional biologists are struggling with these algal compound effects.

 

http://webs.uvigo.es/thalassas/Thalassas%2023(1)/T23(1)_04_%20Rodr%EDguez-Ramos%20et%20al.pdf

 

It may be that the algae grown in waterfalls are from such different habitats than that of the algae in display tanks, these Allelopathic effects work in our favour. Which would explain why lots of people see display algae dying off soon after implementing a waterfall scrubber, even though nutrient tests indicate far from perfect reef conditions. This in fact may be the primary reason (not nutrient reduction) for the effectiveness of ridding display algae. Perhaps the failure of so many UAS systems is due to the fact that the algae grown in a UAS is too similar to display algae. I would however point out I have no evidence of any of the above but it does seem to incorporate a bit of variation into the scrubber process which would explain some of the scrubber failures we see on the scrubber site. Another point to mention is broad leaf macroalgae such as Caulerpa. Caulerpas and such are the dominant macro algae in true reefs, this is because they grow slower and have a greater affinity for nitrogen and phos (able to survive extremely low nutrient levels). But these algaes die in a scrubber maintained system, this should not be the case unless something other than nutrient export is taking place. Food for thought, at least.

 

That would definitely explain my uas failure.

 

I dont think so bud. My uas was leds and so was my display tank.