[leebca]

There seems to be many posts in Reefland.com regarding nitrates and/or the appearance of nuisance algae, microbial algae growth and the infamous hair algae. I've posted this thread in the Saltwater (Fish-Only) Aquariums Forum as to how nitrates relate to keeping marine fishes (not in a reef tank).

There are two conditions that exist which should cause you to continue reading:
1. The nitrate concentration in your marine aquarium is high; or
2. The growth of nuisance algae (e.g. hair algae) or microbial/single cell algae is unsightly and you can't seem to get rid of it.

In the case of 2. the nitrate concentration in the tank could be very low or even undetectable by the home nitrate test kit. The absence of nitrate is a sign that something in the aquarium is removing it (that nuisance stuff) or that it isn't being produced

IMPORTANT or NOT?

There have been many studies done to determine the effects that high nitrate concentrations have on marine fishes. In natural seawater nitrates are very low, usually below detection limits of our test kits. In home aquariums it can reach levels of 200+ parts per million (ppm). It has been shown that a few marine fishes may be visually affected by nitrates slightly above 200ppm. But, are they affected without us knowing it, at lower concentrations? Most experience and testing seem to indicate that marine fishes don't have a problem with high nitrates (under 200ppm).

Some online marine fish sources require that their fish be put into water with nitrates under a specific concentration to qualify for their guarantee of survival. I've seen 50ppm or less, and 75ppm most often quoted, when it is mentioned. Perhaps this requirement assumes that live rock is used in the aquarium, because 30+ years ago, before live rock was used so much, the nitrates would get up to 150ppm in between water changes.

So what should be the target range?


TARGET

Almost everyone can agree that a nitrate reading below 50ppm is okay for a fish-only aquarium. Most can accept 75ppm. My personal opinion is that if nitrates peak out above 100ppm before a water change, there is something lacking in the system (nitrate removers) or the system is producing too much nitrates in general or some of both.

Nowadays with the prevalent use of live rock, keeping a mature fish-only-with-live-rock (FOWLR) aquarium system that isn't overstocked, below 50ppm nitrate should be easy. Not critical, just easy.

Having written this, the reader should realize that high nitrates encourage the types of growth most Fish-Only (FO) aquarists don't want -- micro algae and microbes that utilize nitrates. Hair algae is one unwelcomed 'guest' in even the FO aquarium. Unless there are fishes or snails to eat it, it will use the nitrates, phosphates, etc., to grow and multiply. So the fish might not care, but the aquarist may not want all these 'ugly' growths in the FO aquarium. This requires nitrates to be kept as low as possible -- at least below 25ppm. If there is already these growths in the aquarium, the nitrate level may be low because these life forms are consuming it.

The above applies to a mature aquarium. If the marine aquarium is young (under 6 months) it probably isn't worth worrying too much about the nitrate levels. What the aquarist wants is to see what the nitrate levels are, after the tank matures.

TESTING

Some people like to use the quick dip test strips. They are not bad. But no decision on making changes to the tank or aquarium system should be based upon a reading from a dip stick. As a screening test, the dip stick is okay. So, if the dip stick says that nitrates are high, it is time to bring out the nitrate test kit to perform a more accurate and reliable test.

The tank water tested at or over 100ppm nitrates? Check the test kit for expiration and that you're following its direction properly. Then, no matter how sure you are that you're right, bite the bullet (even if you're a professional) and have someone else test the water for nitrates, hopefully using a different (even a different manufacturer's) nitrate test kit.

OR

You tested and found very low nitrates (less than 5ppm) BUT there is unsightly significant growth of micro algae or hair algae.

Next, think about whether or not your tank can be considered mature. (See: The Mature Aquarium for more details). If the aquarium system is young or recently 'upset' (new additions, sudden death(s), etc.), it will be going through many microbe changes. (See: The Secret Cycle). I would NOT recommend taking any action against high nitrates in a tank/system that hasn't matured.

SOURCES

In the 'start' of the nitrogen cycle, bacteria turn ammonia into nitrite and other bacteria turn nitrite into nitrate. This change of nitrogen into these compounds is referred to as the 'nitrification process' and is the prime role of the biological filter. There it stops unless there are other bacteria to further convert the nitrate to nitrogen gas (and other compounds), or the nitrate is removed from the water somehow. This third group of bacteria perform the process known as the 'denitrification process.' Nitrification and denitrification are parts of the nitrogen cycle. This third group of bacteria metabolize nitrates where there is little oxygen in the water (anoxic conditions) to where there is no oxygen in the water (anaerobic conditions). This is part of the value of live rock. See: Denitrification v. Nitrification, and What is Live Rock, Anyway? for more details.
For our purposes, we'll consider and think that ammonia is required to start the process of making nitrates, so the sources that have to be considered are those sources which would produce ammonia. In general the decaying, rotting, and decomposing of organic materials produces ammonia.

Another source of nitrates is the conscious or unconscious addition of them directly to the aquarium system. So check out these lists:

Nitrates can be put directly into your aquarium from some, all or even more than the following sources:
foods
additives
source water (See: WATER - Source and NSW)
artificial salt
decorations that have nitrates in or on them
equipment not made for saltwater aquariums
use of products in or around the aquarium that contain nitrates

Ammonia and excess ammonia can be produced from some, all, or even more than the following sources:
rotting flesh or addition(s) of organic matter
dead marine life (snails, fish, shrimp, crabs, clams, corals, etc.)
decaying matter (fish fecal matter)
excess organics (some additives have organics in them)
live rock die-off or curing
uncured coral skeleton
rocks and/or substrate that isn't suitable for a marine aquarium
rock and/or substrate that wasn't cleaned (containing wood, paper, molds, moss, dirt, or other organics that will slowly decompose)
overfeediing fish or feeding fish too much at one meal (their fecal matter should not look like it did when eaten)
rotting food (putting in food that goes uneaten)
feeding improper foods that the fish don't digest
detritus (a combo of some of the above in 'clumps' or lose aggregates)
use of cleaning solutions and cleaners that contain ammonia (even in other rooms of the home)
filters that have trapped waste in them and not cleaned often enough
areas of the tank/system where detritus and wastes accumulate
over-stocked aquarium (too many fish and organic waste producing marine life)
using a biological filter that produces an excess of nitrates (or reduces the effectiveness of live rock)
decorations made from materials unsuitable for use in a marine aquarium


WRESTLING THE DEVIL

The best thing to first do after checking the test kit out is to read labels of everything you put into your aquarium. Look for chemicals that contain "nitrate" in their name. Does anything being added encourage the production of nitrates by interacting with other chemicals? Get on the Internet and get the answers. Check the source water for nitrates; test the new freshly made salt water for nitrates before its use. Track down those on the list above for direct additions.

Next, check the list for sources of ammonia. Any in or around the aquarium system? What can be removed or improved upon? Maintenance? Is there a child in the home that think that Nemo would like some Cheerios? Check plumbing and overflows for 'foreign' matter.


NITRATE CONCENTRATION CONTROLS

Mother Nature didn't start something She couldn't finish. As previously mentioned, natural seawater contains little nitrates. There are a few "natural"' ways to reduce or remove nitrates from the marine aquarium system water. There are also a few artificial ways to reduce or remove nitrates from the water. Macro and micro algae live on nitrates. It's fertilizer to them. With some phosphates, trace elements, light, etc., the macro algae will 'eat' the nitrates. After verifying the proper quantity of live rock is in the system, culturing macro algae and/or deep sand beds are favored means of removing nitrates. Culturing macro algae can also supply food for your herbivore fishes if you choose the right macro algae. (See: Tang Macro Algae Foods for more details).

Things that would naturally or artificially reduce the nitrate concentration, such as:
growth of macro algae (in display, sump, and/or refugium)
mangrove plants
refugium (where other organisms can utilize the nitrates from the water)
deep sand bed
micro algae (rather unsightly though)
nitrate reactor (absorbents or, resins or, places set aside for anaerobic bacteria to flourish)
water changes (not good for removing low quantities -- a 25% water change only lowers the nitrates by 25%)
active live rock at 2 pounds per gallon of system water

Many new to the hobby don't appreciate the role that live rock plays in the nitrification AND denitrification process. See this for more details: What is Live Rock, Anyway?.

SUMMARY

Let the aquarium system mature; check the test kit and test procedure; determine the target concentration; track down sources; invest in controls if needed. That's it. This applies to the mature, FO or FOWLR aquarium system. This same process can be applied to a reef system where the nitrate concentration is desired to be zeor, none detectable, or almost zero.

If your system is covered with nuisance algae then one of the best things to do is to introduce macro algae to compete with it for the nitrates. Taking some or all of the other steps to reduce available nitrates will go a long way towards fighting the nuisance 'stuff.' When it is almost under control, introduce snails that like to eat the nuisance stuff and you'll have it under control.

Most of the above does apply to mature reef tanks, except the TARGET would need to be a near 0ppm (under 5 ppm for most non-fish marine life) using the home nitrate test kits. The above should answer most of your questions. If not, just post your nitrate question to this thread.

[mhender]

my test kit has high and low range nitrate results, which one is the correct one to use?

[CSeaSee]

Could you be a little more specific? You want to shoot for zero nitrates...

[mhender]

Yes, 0 ppm would be great. the test kit (red sea) has 6 different color "ranges" to compare the color of the test vial to. on the right of the card it says Low Range and on the left it says High Range. Which is the "range" I use and why is there a High and Low range?

[leebca]

The low range is the one you want to focus upon, since your target is low quantities of nitrates. However, the one to use has to do with the way in which you perform the test. Look closely at the test instructions and you'll find a statement in there that you will alter the sample size or dilution of the sample to use the higher range. I don't use that brand of test kit myself, so don't have anything more specific I can add.

[showfish]

I'm planning on going to the refugium. What type of sand bed is best in a fuge for nitrate removal, and what type algea is best to use in the fuge?

[leebca]

A deep sand bed (DSB) in the refugium will facilitate nitrate removal. Use a depth of 4 to 6 inches. Particle size has some influence on the efficiency of the DSB and the target depth. Avoid powdered sugar sized sand and go with one where the particle size is about 1 mm or so.

The macro algae best known for removing nitrates is Chaetomorpha sometimes written as "Chaeto" and pronounced "kay-toe." This algae grows in medium light and grows proficiently and requires little care. This macro algae is thrown away at harvest/thinning time.

[showfish]

Thanks for the info. One other question, If I'm incorporating this refuge in an already mature tank, do I need to cycle the fuge before I tie it into the main display? There seems to be conflicting points of view on this subject. The way I see it, if it is going to filled with 4 to 6 inches of live sand, why can't I just let the sand settle, tie it in, and let it flow.

[leebca]

If the aquarium is biologically self-sufficient, then the refugium may be added in line as soon as it is ready. The assumption is that the refugium is not contributing to nitrification. The concept of a DSB with 'live sand' is erroneous speaking in terms of 'live' being seeded with nitrifying bacteria. Live sand is not needed for a DSB since its primary function will require not the nitrifying bacteria but the denitrifying bacteria. Just buy off-the-shelf substrate, not living substrate.

[Bianca]

Originally Posted by leebca

If the aquarium is biologically self-sufficient, then the refugium may be added in line as soon as it is ready. The assumption is that the refugium is not contributing to nitrification. The concept of a DSB with 'live sand' is erroneous speaking in terms of 'live' being seeded with nitrifying bacteria. Live sand is not needed for a DSB since its primary function will require not the nitrifying bacteria but the denitrifying bacteria. Just buy off-the-shelf substrate, not living substrate.

There is a Pet store not far from me that has a 40 gallon tank with some plastic coral ,plastic sea trees but an undergravel filter that the guy NEVER vacuums but does water changes the crushed coral is all green just algae it looks like algae carpet.

Thus not biological imagine no flow either (its air stone flow with 4 tubes).
You think its working as an algae type filter ? Or not working at all just his 4 seahorses are doing well due to water changes?

Thanks

[leebca]

I don't know the size of the seahorses, however 4 is generally not a heavy bio-load. An old 40 will have a lot of surface area and there could be enough bacteria in the areas of water movement (on glass/aquarium sides, decorations, tubing, etc.) that can/are handing the nitrogen waste products.

If the tank is well established (old) it could very well be fairly stable. However, all it takes is a shift in the balance and the system can crash. That is, the system is marginally stable and without enough 'back up' bacteria to handle a significant change.

If anyone decides to clean it, best to do 1/5 of it at a time.

The undergravel filters are surprisingly hard to defeat providing the depth is commensurate with the size of the substrate pieces. Old, uncleaned, and/or blocked are certainly ways to defeat their function. To say it has no flow would mean that the airstone is not causing water to rise in the tube(s). That would have to be looked at very carefully to see if there is truly no flow.

The water changes, depending upon volume and frequency, would determine how much dissolved nitrates, phosphates, and organic wastes are being exported. The algae obviously indicates it is being fed some nitrates and phosphates and possibly other organics. But, I don't know if nitrates bother seahorses or not. They are one of the marine lifeforms with which I haven't any experience. You didn't mention if there is a skimmer on the tank/part of the system. That would account for some export of organics, phosphates, and nitrates.

The 'algae' may be suspect, in of itself. Is it really algae? or mixed with other microbial lifeforms? The lighting would play a role on what microbial lifeforms may be encouraged in such a system.

It would be interesting to test the water before one of the 'regular' water changes for nitrates and phosphates, in addition to a few other chemistries, to see what might be happening. Then I'd like to examine the 'algae' under a microscope and see photos of the 'mat.'

Lastly, if the LFS isn't removing any of the algae, then these nutrients aren't being exported, only 'trapped.' That can be another source of a crash. Certainly, luck has a role in our hobby, but the system you described could be pushing it!

[Bianca]

Thanks for the info.
I guess there is water flow as the air stones he changes and the tank does have water movement.
He never touches the bottom but yes 4 sea horses arent crowded . The light is from a flourescent full bulb but the tank gets light from window also.
Store has AC ofcourse so not hot. The tank is 4 yrs old and sea horses are old to. He changes bucket of water with ocean water he picks up in Key west by the bales .
I was tempted to ask if I could clean it for him but got scared as it was working well. Going to see if I can get a picture of it as find it unusual UG filter never vacumed and tank sea horses look great.

Thanks