Worldreefs.info – Roiy's Reef

Alkalinity – What Is It and How Is It Controlled

Written by John Cunningham Thursday, 19 March 2009 09:14

This is not a complete scientific discussion or description of alkalinity. It is simply intended as a base, as there isn’t a requirement for an aquarist to be a scientist and understand all. A basic understanding allows the aquarist to ensure the seawater in his/her aquarium is at the parameter desired and why.

Right, that said, alkalinity then. Alkalinity of seawater is the ability of the seawater to resist certain change. Alkalinity can also be called Carbonate Hardness. Seawater is on the alkaline side of neutral. To quickly describe this, pH is measured on a scale of 0 to 14, with 7 being neutral. Above 7 is into the alkaline side, below 7 is into the acidic side. Aquarium seawater is, generally, maintained between 8.0 and 8.4. So, as can be seen aquarium seawater is on the alkaline side.

Alkalinity resists changes towards the acidic side of the pH scale. Another way of putting this is that it ‘buffers’ the seawater – it has an acid binding capacity. The life cycles etc within the aquarium are continuously trying to push the seawater towards the acidic side, and this push is cancelled out by the buffer capacity of the seawater. This buffering is enabled by carbonates and bicarbonates.

The alkalinity of water is measured in either dKH, meq/L, or mg/l. (If it is wished to convert dKH to mg/l, simply multiply dKH by 17.9.) Whichever scale you choose does not really matter. They give the same answer with different numbers, in the same way that distance can be measured in miles or kilometres. Test kits are readily available and will give instructions, and come with a table so the reading can be easily obtained. It is important to follow the instructions carefully.

Natural seawater has a measurement of around 8 dKH. (143.2 mg/l). The sea has an enormous volume, and in the aquarium it is better to maintain a reading of between 9 and 11 dKH (161.1 and 196.9 mg/l). It should not be necessary to raise the seawater alkalinity higher than 11 dKH.

Having measured the seawater, if it is decided to increase the alkalinity level (for example, because there is a low pH reading), this can be achieved by adding carbonates and bicarbonates (adding ‘bases’, this is the opposite of adding acids). These are available commercially, and are easily applied. The products are often described as KH and/or pH Boosters or Buffers. Do not attempt to raise the alkalinity too rapidly, follow the manufacturer’s instructions for the net gallonage of the aquarium. Changes in the marine aquarium should be gradual.

The maintenance of a good alkalinity level has great benefits. It not only protects from drops in pH, it can help keep corals, particularly hard corals, in good health and assist the growth of colourful encrusting algae.

Routine water changes, proper seawater circulation to allow gas exchange etc, and routine measurement of parameters including pH and alkalinity will help maintain a beautiful display aquarium. Once the aquarium has settled and matured, the aquarist may feel the water testing regime can be relaxed. This is fine, although occasional testing should still take place. Any sign of deterioration, overall water testing should be initiated.

Those who might wish to read a little more should follow this link, which is interesting and straightforward:

http://www.advancedaquarist.com/issues/nov2002/chem.htm

It is also recommended that along with alkalinity, the aquarist should have a look at the meaning and control of pH.

John Cunningham is co-author of Aquarists Online and co-founder of Aqua Compare. Visit Aquarists Online if you are interested in learning more about keeping a marine aquarium or Aqua Compare if you are interested in comparing aquarium prices.

Natural Seawater – Is It Recommended

Written by John Cunningham

Thursday, 19 March 2009 08:53

Mother Nature provides the habitat for the livestock that we aquarists keep in our fish only aquariums or reef aquariums, and this, of course, is the wild reef. Mother Nature is also the provider of the other obvious essential, and that is seawater.

Having written the above it would seem absolutely wrong to state that natural seawater is not recommended. So it would be – natural seawater is recommended.

However, is it recommended overall, for the majority of aquarists? This needs a bit more care, and two questions arise. These are first, the ability to collect the seawater, and, second, before any attempt is made to collect it, what is the seawater’s condition?

Not all aquarists live within easy travelling distance from the sea, but there are a fair number where it could be a viable proposition. So in this case the first consideration is practicality.

Seawater is heavy, it ways somewhere towards 10lbs per gallon. So to do, say, a 10% water change a good few gallons are required. Not so many for a nano aquarium, but increasingly more as the aquarium gets larger. Also of course, some aquarists do water changes that are more than 10%.

This water has to be moved from the sea to the aquarist’s home. This means there needs to be sufficient containers of seawater safe construction which are also strong enough for the journey. In addition there must be transport that is robust enough, and roomy enough, to carry the full containers.

If the aquarist cannot meet these requirements then the obvious answer is to use one of the available commercial dry salt mixes. Transportation problems for these mixes are zero as they come in different size packs, can be transported by car, or can even be delivered to the aquarist’s home.

If the aquarist can meet the transportation need, then another consideration arises. This concerns the question of pollution. It is very unfortunate that many coastal areas are polluted with industrial waste and/or agricultural run-off and the like. The aquarist must be absolutely sure that the seawater being collected is clean. There might be a facility nearby who could advise on this matter. If not, it is better to play safe and use a dry salt mix.

If the coastal water is polluted, then natural seawater could still be used. By going considerably offshore, it is possible or maybe probable that the seawater will be unpolluted – but not definitely so. Again, the aquarist must be certain of the condition.

Going offshore brings the transportation problem back. Is there a boat available? If the aquarist is also a yachtsman all is well and good. If not, the only means is to hire assistance, and then cost is creeping in. In the latter case, the effort may not be financially worthwhile, so again a dry salt mix could be the preferred option.

Using natural seawater brings up another possibility, and that is disease or the introduction of unwanted life. This applies particularly if the natural seawater being obtained is warm.

This danger can be minimised. The collected seawater can be kept in the containers in the dark for a week or better two, and at the same time have it passing through UV (ultraviolet) lamps. These can be obtained specifically for aquarium use. If there were more than one container, they would have to be connected or the aquarist would need more than one UV lamp. After the mentioned period, the seawater could be used after where necessary being heated to the required temperature, and after any sediment that had accumulated on the bottom of the container(s) had been siphoned out.

There is one more consideration. This is that the seawater could still need supplementation. Just because the seawater is natural does not mean that in a reef aquarium there will not be a need for calcium addition and the like. In the confines of the aquarium, a heavy demand will have the same effect as it would if synthetic seawater were in use.

Some aquarists have reported that using natural seawater has a wonderful impact on their captive reefs. This is of course anecdotal but there isn’t any reason not to accept the reports. Perhaps there is some ‘magic’ in natural seawater that makes a difference?

Looking at so many captive reefs that use commercial salt and can be viewed on the internet and in reality, and considering the great success and beauty of these reefs, there isn’t any real need to doubt modern commercial dry salt mixes.

If the aquarist can meet the demands for using natural seawater, then all is well. Most aquarists will be happy using commercial salts.

John Cunningham is co-author of Aquarists Online and co-founder of Aqua Compare. Visit Aquarists Online if you are interested in learning more about keeping a marine aquarium or Aqua Compare if you are interested in comparing aquarium prices.

AQUARIUM LIGHTING

When choosing lighting for your aquarium (especially reef or Nano reef), there is much more to consider than watts per gallon. The 3-4 watts per gallon for a Nano reef or freshwater plant aquarium, less for fish, more for hard coral; is a start but that is very general. There are other factors effecting lighting for your aquarium than just watt output. For example: You cannot compare the output of a 150 watt Metal Halide to a 150 watt outdoor floodlight. What I am trying to say is sometimes it comes down to comparing apples to oranges. In my experience (and admittedly anecdotal), I have found great variations in light bulbs, I have had 20,000K 20 watt bulbs out perform 7500K 36 watt bulbs in my reef aquariums. And the 20,000K 175 watt Metal Halide bulbs have out performed everything I have tried.

Here are two other important factors;

[1] KELVIN RATING (such as 10,000K daylight bulb):

Although I do not believe all the manufacturers are totally honest about true Kelvin output, I believe it should be considered. Kelvin is used to define the heat or energy output of a bulb and if this is applied to two 36 watt PC bulbs, one 6500K the other 10,000K (often daylight or power glow), the 10,000K bulb has a higher energy output.
What the true definition of Kelvin is that is a unit of measure of temperature on the thermodynamic (absolute) temperature scale.
Here is a brief description of Kelvin:
Kelvin is defined by two points: absolute zero, and the triple point of pure water.
Absolute zero is defined as being precisely 0 K and –273.15 °C. Absolute zero is where all kinetic energy (motion) in the particles comprising matter ceases, and they are at complete rest. At absolute zero there is NO heat energy.
The triple point of water is defined as being precisely 273.16 K and 0.01 °C.

Here are a few Kelvin numbers:

*Absolute zero = 0K (-273.15C)

*Waters freezing point = 273.15 K (0 C)

*Waters boiling point = 373.1339K (100C)

[2] THE NANOMETER RANGE (SPECTRUM)

An actinic bulb will have a Nanometer spike at about 420N, a UVC bulb about 265N, a daylight bulb about 700N is used to measure the wave length of light energy from cosmic rays to radio waves. The difference in the wavelength determines how the wave affects its surroundings. It is this wavelength difference that allows short-wave x-ray to pass through walls, while longer-wave visible light cannot pass though the same material; short-wave ultraviolet and x-ray can destroy DNA in living microorganisms and breakdown organic material while visible light will not. Nanometers: Measuring Light Energy All light energy is measured on a "nanometer" (nm) scale. Nanometer means one-billionth of a meter.

This applies to aquariums when we consider the light spectrum and how it applies to our aquariums individual needs: Red light is the first to be filtered out and can only penetrate a short distance. As light waves penetrate deeper into the water, orange and yellow are lost next. Of all the colors of the spectrum blue light penetrates the deepest. Corals need intense equatorial UVA (actinic) and even some UVB as recent articles (and my own experience) suggest. Most plants both actinic and infrared spectrum.

The Nanometer scale and Kelvin temperatures come together when applied to aquarium lighting this way; Natural sunlight on a clear day registers at 5500 Kelvin degrees. Kelvin temperatures less than 5500 become more red and yellow and the higher the Kelvin temperature the more blue the light is. Most photosynthetic invertebrates should be kept with lamps of a 20000K rating. Actinic emits a fluorescent blue light and is usually used as supplemental lighting. Not only is actinic lighting beneficial to photosynthetic invertebrates, it is also aesthetically pleasing to the eye when used to supplement "daylight" lighting. Freshwater aquarium plants benefit from lighting with a Kelvin temperature in the range of 5500 – 6500 degrees. Freshwater plants prefer light with more red and yellow in the spectrum. What the exact Kelvin output of an aquarium bulb is takes a little faith in the manufacturer (at least in my opinion), as it is difficult to test each manufacturers claims of Kelvin and the application of Kelvin to aquarium bulbs takes a little bit of scientific stretching (based on the definition of Kelvin).

SUMMARY:

A basic freshwater fish tank does not need as much lighting and will often do well with one “Aqua Glo”, “Color Max” or similar (30 watt, 350- 750N, 6500K) light for a 60 gallon aquarium.
A basic saltwater fish tank also does not have as high of requirements, but more than freshwater (especially if you do not want too much brown algae). A “Coralife 10,000 K” or “Hagen Power Glo” or similar (30 watt, 350- 750N, 10,000K) light for a 60 gallon aquarium.

A freshwater plant aquarium needs more actinic and infrared as well as more watts of light. Four 36 watt with half the bulbs being “Flora Glo” (2800 K 700N +) and half being 10,000K bulbs has worked well for me. Incandescent bulbs have a high infrared output and do well with plants, but also put out a lot of undesirable heat. Cool white fluorescent bulbs should never be used in any aquarium as they only put out visible light and not the spectrum needed by plants or even fish. A better choice would be the newer SHO Bulbs.

A basic reef or Nano reef aquarium usually does well with 50/50 bulbs and/or combinations of 10,000 K, 20,000K and actinic bulbs. In a 10 gallon Nano Reef, two 18 watt Power Compact bulbs will usually do well. Make sure all bulbs (especially in exposed situations common to Nano Reefs are kept clean of water deposits and changed every six months.

An advanced Reef with hard corals needs a combination of metal halide and standard fluorescent or PC bulbs. On a 60 gallon reef aquarium I generally used one 175 watt 20,000K metal halide and one 10,000K daylight (40 watt) and one 6500K actinic (40 watt)

Another point about lighting in general is that higher wave lengths of light such as UVA do not penetrate glass well or even acrylic. I recommend direct lighting (best), quartz or polycarbonate where UVA is essential. Just make sure to clean your bulbs or polycarbonate tops regularly to prevent build up that will block light .

For my full Aquarium Lighting article with more information, graphs, including applications for Freshwater, saltwater, freshwater plant, nano reef, and advanced reef, please visit this URL:
Aquarium Lighting; Kelvin, Nanometers and more