Water Chemistry

scotty

scotty

Member
Chicago Fish and Coral Company have a blog on their website. Parts omitted are the sale of testing in their store, if you wish to have an unabridged version, it is on:

http://www.chicagofishandcoral.com/blog/

They put together a three part analysis of water chemistry that I will share below because I think it's a hugely informative piece, and will help when we have people later on asking the same questions over and over, we have something to point them to, I did the leg work, now they gotta read.

Water Quality pt. 1
7th Jun 2010 | Posted in: Water Quality 0
We will spend the next few weeks looking at ways to improve the most important component of all our aquariums…WATER. Each week we will touch on an aspect of water quality, and particularly how some of these pertain to summertime aquarium maintenance. We will also be putting on sale the products we will be talking about.

Summertime and your fish tank

Summer is now upon us, and as it heats up outside it’s easy to spend less time attending to our tanks than in the cooler months. The killer B’s – Baseball, Barbecues and Backyards – take a good deal of time away from your fish tank. Water changes seem to become less frequent, maybe the fish don’t always get fed on time. Also the warmer temperatures can bring problems to reef tanks without chillers as water temperatures can rise dramatically.

So first off, when was the last time you tested your water?

I admittedly had not done a test on my own tank for quite a long time. The other day I went ahead and did a complete test and discovered that I had a phosphate problem. Even with using a refugium and RO water for both water changes and top-off, phosphate can build up in a tank over time. Remember that what we feed our tanks becomes organic waste matter, whether its inhabitants eat it or not, and is a large source of nutrients such as phosphate. Rather than a large water change, I added some chemical products to combat the problem. A week later corals responded with more polyp extension and algae was not growing as quickly on the front glass.

While chemical products such as phosphate/nitrate removers or other similar absorbers are not substitutes for good husbandry, they can be useful in a pinch, and may prolong the time needed between water changes.

The standard water test includes:

PH

NITRATE / NITRITE

AMMONIA

PHOSPHATE

CALCIUM

ALKALINITY

Water Quality pt. 2 - Ph
22nd Jun 2010 | Posted in: Water Quality 1

phScale_99988.gif



pH, it goes up, and it goes down. Sometimes it can change over the course of a day, other times over months. Our fish,of course, would prefer that it doesn’t change at all. So why does it change, and what can we do about it?

pH Basics (and Acids)

Loosely defined, pH is a measure of Hydrogen ions in the water, and the lower the pH, the more acidic the water is. The scale ranges from 0-14, but in a saltwater tank we’re focused on a small portion of this range, between 7.6 and 8.4. This may not seem like much, but the pH scale is logarithmic (much like the Richter scale), meaning a pH of 7.6 is almost ten times more acidic than a pH of 8.4!

A fish-only system can actually tolerate a pH anywhere in this range, provided it is stable, and the fish get accustomed to it slowly. This is a major reason why we have to acclimate fish (and invertebrates), as even a small change in pH can be quite a shock. Reef systems are a different story, as their inhabitants require a narrower pH range, between 8.0 and 8.4, and are less tolerant of pH changes.

The task, then, of controlling pH can seem difficult, and it is complicated by the fact that aquariums have a tendency to become more and more acidic over time. This is because acids are constantly being added to the water, in the form of CO2 from respiration, nitrification by way of biological filtration, and organics from foods and biological waste. These acids lower the overall pH of the water, sometimes drastically.

Luckily, both marine and freshwater systems have a means of naturally combating this acid attack. Alkalinity (aka carbonate hardness, KH, or dKH) is a measure of carbonates, which provide a buffer that can slow changes to the pH of the water. In reef systems, these same carbonates are utilized by corals to build their skeletons and can diminish overtime, so it is especially important to keep a close eye on alkalinity and pH. To be brief, you should aim for an alkalinity between 7-11 dKH depending on the system. The higher the alkalinity, the more buffering capacity, and the more acids the system can handle. If the level of carbonates becomes too high however, it can disrupt the ability of other compounds to remain dissolved in the water, throwing off the overall balance.

In both fish-only and reef aquariums, when the pH starts to drop, it is usually an indication that the buffering capacity of the water is getting worn out, and the increase in acidity needs to be corrected.

Ways to Stabilize and Solve pH Problems

Change your water! – This common-sense tactic is our favorite method of raising and/or stabilizing pH and dKH levels, because regular partial water changes refresh the natural carbonate buffers and restore other major elements in the water column. Remember, what you put into your tank in the form of fish (respiration) and foods (organic waste) must be removed or neutralized so you can maintain a high pH and clean environment, and this is the easiest way to accomplish it.

The Quick Fix – There are many good pH stabilizers and adjusting products on the market that are suitable for a wide range of situations. These products come in either powder or liquid form and many can be added by dosing on a regular basis without raising the pH above 8.4. It should be noted, though, that some of these products raise alkalinity as well as pH. Since excessive usage can raise both of these to dangerously high levels, it’s important to test both alkalinity and pH periodically when following a dosing regimen.

Even if you are not currently on a dosing regimen or have a pH problem, it is a good idea to have a pH stabilizer on-hand, as you will never know if/when you will need it.

Calcium Reactors/Automatic Dosers – These are expensive solutions to control pH and alkalinity. Reef geeks with larger systems love these contraptions because they provide a consistent environment to their vast array of corals. While these systems do work, for many hobbyists they are simply an added expense and liability, so we only recommend them for larger systems with a high coral population.

Testing and pH Buffer Specials

Once again start with the basics. If you are not testing your pH, you don’t know if it is a problem.
 
Water Quality pt. 3 - Nitrates and Phosphates
27th Jul 2010 | Posted in: Water Quality 1
Nitrate and Phosphate are always present in the aquarium. Where there is fish, fish food, and subsequently – fish waste, there will be nitrate and phosphate. From time to time even the best of us get too much of these in our aquariums, especially in the summer when we pay less attention to our tanks. So how can we keep nitrate and phosphate under control in the aquarium?

What can I do about it?

There are a number of methods for reducing both nitrate and phosphate in an aquarium. Luckily, many of these methods work on both at the same time. These methods happen to fall under the same categories we use to classify filtration: physical, chemical, and biological.

Physical

The first of these methods is water changes. Physically removing water with the troublesome compounds and replacing it with clean water will lower their overall concentration in the system. You can also vacuum your substrate at the same time to remove accumulated waste not consumed by your cleanup crew. If not removed, this waste can continue to decompose and add more nitrate to the water. We should note here that it is important to make sure the water you are using for your water changes is indeed free of impurities. Nitrate even in tap water is rare, and usually the culprit is phosphate. Using distilled or reverse osmosis (RO) water will ensure that neither of these compounds are present. We sell both RO water ($.50/gallon) as well as premixed saltwater ($1.00/gallon) if you are looking for a no-nonsense way to do water changes.

This next method, while not able to actually reduce nitrate or phosphate once the compounds are already in the water, can help them from accumulating in an aquarium in the first place. Protein skimming has the capability to remove organic waste from the water before it has a chance to break down into its chemical components. In short, organic compounds stick to the surface of the bubbles within the skimmer chamber, and the subsequent foam rises up out of the water column and out of the system. A protein skimmer will not catch 100% of these compounds, but enough of them to reduce the rate at which nitrate and phosphate accumulate in the system. These are helpful devices to have on most any aquarium, and will help keep your water cleaner between water changes.

Chemical

Another method is to use chemical absorbers. The absorbers are usually contained in a physical medium that works much like activated carbon, but is geared specifically toward nitrate or phosphate (and sometimes both). Nitrate absorbers are best used temporarily since it’s easier in the long run to address the cause of excess nitrate rather than just treating the symptom. These absorbers, much like activated carbon, can indiscriminately absorb chemicals including those we may want to keep in the water. Phosphate specific absorbers on the other hand can be used on a regular basis if need be. These come in either aluminum or iron based forms. Aluminum based remover is the less expensive of the two, but generally becomes saturated after a couple days and must be removed before it starts releasing the phosphate back into the water. Iron based remover can be used continuously, whether in a media bag or media reactor with water constantly flowing over it.

Biological

Reducing nitrate and phosphate biologically can be as simple as adding more live rock or sand to the aquarium, or as complex as adding food for nitrate and phosphate eating bacteria. On the simpler end, both live rock and live sand have the ability to naturally reduce nitrate. Deep within rocks and at the bottom of sand beds live anaerobic bacteria that can actually transform nitrate to nitrogen gas. If adding more rock or sand is not desirable or not possible, we carry commercially made nitrate-reducing media that can accomplish the same ends.

Refugiums are another possibility if space is available. They can be in any number of configurations from separate tanks to areas set aside in the main tank to grow macroalgae. It’s this macroalgae that feeds on nitrate and phosphate (much like nuisance algae does), but at a much higher rate. It can not only help you reduce the levels of both of these compounds, but can essentially starve undesirable algae at the same time.

A method gaining in popularity in recent years involves feeding bacteria that also feed on nitrate and phosphate. This ‘food’ encourages the growth of certain bacteria to a higher level than would naturally be found in an aquarium. We carry a liquid version of this product and find it useful on smaller aquariums where nitrates tend to be more of a problem.

Which method is right for me?

That depends on what it is you are trying to accomplish. If you regularly test your water and notice a sudden increase in nitrate or phosphate, a short term solution like a chemical absorber along with a water change will give you time to find the cause of the problem. If like most of us you either don’t do water changes as much as you should, or find nitrate and phosphate accumulating faster than you’d like, any number of these solutions could be applicable. The most effective method (though not necessarily the cheapest) would be to perform water changes more often. Adding a protein skimmer and/or a refugium can help prolong the time between water changes. Some tanks, even with very frequent water changes, may still accumulate these compounds too quickly, which could be a sign of overfeeding or overcrowding. Reducing the number of fish, the amount of food those fish receive, or upgrading to a larger protein skimmer could be a solution there.

Every situation, like every aquarium, is different. If you need help deciding which method is the best for your aquarium, feel free to stop in the store, email us, or give us a call, we’re happy to help.
 
Water Quality pt. 3 Cont'd

What are they and where do they come from?

Both nitrogen and phosphorus are present in fish food, as they are two of the building blocks of organic matter. Each time we feed our fish, we are adding them to the system. Additionally, each time a living organism in the tank dies and decomposes, the nitrogen and phosphorous in its body are gradually released into the water.

Nitrate develops through a few stages, all part of the natural nitrogen cycle. Nitrogen first enters the system as ammonia (NH4) from decomposing animals, food, or waste. Bacteria consume the ammonia and produce nitrite (NO2). Other bacteria consume the nitrite and produce nitrate (NO3). This is usually where the cycle ends, as many aquariums do not house the bacteria necessary to process nitrate into nitrogen gas.

Phosphate will usually enter the water as an inorganic compound, whether as a result of decomposition, or from top-off/water-change water with phosphate in it. Unchecked, the levels of both of these chemicals will continue to rise in a closed system like an aquarium.

As we discussed in our previous post, both nitrate and phosphate can be removed chemically and biologically, as well as through water changes. Under normal circumstances, phosphate can really only be reduced through uptake by plants or algae. This is because phosphate in its final form is inorganic, so either gets used as fertilizer or else just sits there. While some bacteria do consume phosphate, there are so few of this type of bacteria naturally occurring in the average aquarium that it doesn’t make much of an impact on the overall phosphate concentration in the water.

Nitrate, on the other hand, can be removed biologically through a number of methods:

Denitrification

Just as some bacteria thrive in high oxygen environments (in bio-balls for example); others live in low oxygen environments. These are the bacteria we want to nurture, because they will consume nitrate and produce nitrogen gas, which bubbles harmlessly out of the water. Creating these anaerobic areas usually requires adding more live rock or sand to an aquarium. Deep within the rock and at the bottom of a sand bed very little water flows, limiting the amount of oxygen. If however water flow is too slow (i.e. too much rock or sand that is too deep) this bacteria will quickly consume the available nitrate and move on to other molecules such as sulfate. The bacteria convert this sulfate into hydrogen sulfide (H2S), a toxic gas that can have devastating consequences if released into the water. These anoxic (no oxygen) areas where hydrogen sulfide is likely to be present will appear black, due to metals the gas reacts with.

Nitrate Assimilation

Ideally, much of the excess nitrate (and phosphate) in a tank will be used by plants and macroalgae that you want living in the aquarium. While plants take up these molecules through their roots, and algae get it directly from the water, they both retain nitrate (and phosphate) in larger compounds within their bodies. This means that the compound is still present in the system, ready to be released again if the plants or algae die and decompose in the tank. To remove the assimilated nitrate from the system entirely, the algae must also be removed.

Carbon Dosing

As mentioned above, there are some bacteria that naturally use phosphate, particularly bacterioplankton (bacteria in the plankton layer). Bacterioplankton’s uptake of both nitrate and phosphate is relatively low compared to the rate at which those molecules are added to the water. But by adding carbon (usually as a sugar such as ethanol) we fuel the bacterioplankton, increasing their appetite and number. This can substantially increase the amount of nitrate and phosphate used by the bacterioplankton, which is then bound to larger compounds that can be removed via protein skimming.

Can too little of a ‘bad’ thing be bad?

As aquarists have gotten better at maintaining aquatic systems, we have developed more efficient methods of reducing pollutants in the water. As a result, it’s easy to get a bit too overzealous in our quest to strike down nitrate and phosphate altogether on the behalf of the creatures living in our tanks. Unfortunately, there’s a tendency to forget that, in addition to all the fish, invertebrates and corals, we actually care for one additional organism: the aquarium itself. If we hope to someday attain the nirvana of a self-sustaining system, it’s important to realize that these systems are immensely complex. Everything seems to affect everything else, and two dissimilar elements like nitrate and phosphate can be locked together in a balance that we can easily disrupt with too much meddling, damaging the entire system.

Such imbalance is clearly seen in aquariums where heavy protein skimming, macroalgae, phosphate absorbers, and carbon dosing are all employed, and hair algae are still present in the system. Since all these methods work to reduce nitrate and phosphate, one would think there wouldn’t be enough of either for nuisance algae to grow. What is likely happening here is that these methods are fighting each other for dominance, not working up to their full potential, and allowing the algae to grab a foothold. Carbon dosing can be particularly guilty of this, as it influences an already poorly understood bacterial balance in our systems.

It may be necessary at times to take a step back and remember that proper management can allow the system to do some of the work for us. A measured approach to caring for the living being known as a reef aquarium should take into account the input into the system (nutrients, fish, etc.) and its natural ability to export (nutrient assimilation, nitrogen gas exchange). Outside help in the form of water changes and the occasional mild correction should always be expected, but sometimes a little nitrate and phosphate never hurt anyone.
 
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