Your reef tank's eco system depends on the proper balance of feeding and filtration. More recently the industry has gone through a period of revelation where many have come to the realization of the deleterious affects of under feeding and over filtering the water. Indeed, at Reef Chaser's we have seen clearly for ourselves that the systems prefer to have slightly elevated nutrients versus being stripped of them entirely. It's important to feed your fish. It's important to feed your corals. In fact, your Reef Tank WANTS you to feed it, and you definitely should! When you do you'll definitely notice positive results. We prefer to feed our tanks small and frequent throughout the day, but other schedules may work just as well (such as once or twice per day, but larger amounts). For us, the driving factor in our food schedule is ultimately to maintain Nitrate and Phosphate levels naturally, without the need of inorganic dosing which would only do as a last resort. 

The unfortunate truth is, over-feeding and under filtering can also have deleterious affects and there for the balance between these two becomes one of the most important aspects of maintaining a successful Reef Tank. In this article we will discuss our strategy and the various filtration elements that make it possible and approach to these issues and how we strive to achieve balance every day.

Quick Index

Water Changes

The solution to pollution is dilution! Water Changes can have an immediate impact on the nutrient levels in your system. A 25% Water change will instantly reduce your nutrient levels by 25%. One of the easiest and simple ways to combat rising nutrients in your tank is with a simple water change. Water changes should always be your first form of control but we will assume that you've already been told all about water changes and the great impact it can have on the overall water quality and health of your system. For the majority for of this article, we will focus our time discussing other things. 

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The strategy we implement at reef chasers is HIGH INPUT and HIGH OUPUT. What does that mean? It means we feed a lot and we filter a lot too in order to achieve nutrient balance and stability via natural feeding and not inorganic nutrient dosing. 

We don't have want to have to worry about feeding our systems, or our corals, as it keeps them healthy. As such we must take great efforts in planning our filtration so that we don't have to worry about it. This often involves implementing multiple forms of filtration such as Biological, Mechanical and Chemical techniques and most likely a balance of all 3.

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How much nutrients do I need?


Elevated nutrients are typically a good thing for your reef tank despite popular beliefs perpetuated on the internet. Our recommendation is to maintain nitrates at around 5-10ppm and phosphates at around 0.05-0.1ppm. You should never let either of these hit zero. Zero phosphates will lead to nasty nuisance algae infestations, specifically Dinoflagellates which are nasty and difficult to deal with. When Dinos and other nuisance algae's set in, coral health can deteriorate quickly.

For testing, we recommend keeping nitrate simple with a Salifert Nitrate Test kit (simple, easy) or something like a NYOS nitrate test kit. For phosphate, we need to get more accurate at smaller concentrations so we are really going to want a digital tester. We recommend using Hanna Phosphorus ULR (Ultra Low Range which will give you reading in phosphorus ppb, and a chart to convert that to phosphate ppm (Multiply ppb phosphorus by 3.066 then divide by 1000 to equal ppm phosphate)

Our overall strategy is to keep these as stable as possible although like every system, even ours will go through peaks and troughs. In fact, it's why we want to keep them slightly elevated but not too elevated. This will allow room for the peaks and troughs. 

We would panic if we saw 0/0 on our daily test results, but as a general rule of thumb we do not take any action until a second day of tests confirms the results. Too many times a test one day will show a peak, only to return to normal level on its own the very next day. If we were to take action every single time we saw a test result that was slightly elevated, or slightly low, we would be playing mad chemist daily on reef systems.  One thing to know for sure is that mad chemistry doesn't make for great stability. 

Every system is different, and overall stability is the most important factor. Sudden changes in nutrient levels can have deleterious effects. We have seen examples of successful Reef Systems with as high as 20+ nitrates (Although we don't recommend it) and .5+ ppb phosphate. Why this works for some and not others is a great mystery within the hobby.

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What if my nutrients are too HIGH?


There are 3 ways to control nutrients in your reef tank. Mechanical filtration, Chemical Filtration and Biological Filtration. A balance of all 3 of these often leads to the best results. 

  • Mechanical Filtration includes things like Skimmers (protein fractionators), Filter Socks, Floss, or mats, Trickle Filters or Sulfur Filters, Activated Carbon, GFO (Granular Ferric Oxide) and of course, WATER CHANGES!
  • Biological Filtration includes things like Chaetomorpha Algae or other macro algae and Bacteria, Bio-Pellets are a hybrid form of Bio and Mechanical filtration.
  • Chemical Filtration may include things like Lanthanum Chloride (Phosphate binder sold under brand name Phosphate-E), Organic Carbon Dosing (NoPox, Vinegar, liquid does  not to be confused with activated carbon), Ozone

If you have elevated, balanced nutrients and are still experiencing an algae problem it may be worth exploring solutions like Flucanazole (turf/bryopsis) and Algaefix (allegedly reef safe if dosing instructions are followed. We don't use this at Reef Chasers, but would consider using it if Algae was out of control to the point it was actually affecting coral or system health). As we know, Algaefix's active ingredient is the chemical Busan 77 and it has been theorized by the community this is the same active ingredient in popular algae-killing product "Vibrant"

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What if my nutrients are too LOW?


FEED, FEED, and FEED! This is the best way to maintain the levels naturally which we always prefer to do. You can also dose Nitrate and Phosphate directly although we feel organic sources such as food is the best solution.  The only issue with feeding is that it tends to raise both Nitrate and Phosphate and there could be circumstances where one is high, and the other is low. In those circumstances, individual dosing of the Nitrate and Phosphate can be preferred to achieve balance. Once the balance is achieved then you can maintain it naturally with heavier feeding.

What you will find by keeping your nutrients elevated is less nuisance algae like Golden Algae, Dinoflagellates, Hair algae and Bacteria. Although it's possible to grow algae problems with high nutrients, it is often less trouble some varieties.  The reason for this is that when nutrients are low/depleted, only the edge competitors can survive. This means nasty algaes and bacteria like those described above and NOT the things we want to thrive, like our corals. When your system is starved for nutrients, bad things can and will set in. 

The good news is, it's easy to fix just FEED!!!!

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This can be a topic of confusion among new hobbyists. When we are talking about organic carbon dosing we are talking liquid dosing. Commercial products like NOPOX are a popular form but there are recipes online for at home DIY which use simple vinegar as the organic carbon source. When we are talking about Activated Carbon we are talking about the black-charcoal that people use in things like media reactors or alternatively in media bags placed in high flow areas of the sump. 

Organic carbon acts as steroids for your reef tank's bacteria. Organic Carbon sources like vinegar send them into hyperdrive, as they gobble up nutrients like nitrate and phosphate along with the organic carbon. The elevated levels of organic carbon allow them to bloom and this can have a dramatic effect on nutrient levels in your reef. We recommend starting dosing conservatively and err on the side of caution. Vinegar is an Acid and at small doses will still have a small effect on your reef tanks pH overall. For this reason we recommend dosing the organic carbon during the day instead of at night. Remember that organic carbon dosing will reduce both nitrate AND phosphates so if only one is high it is important to supplement the other while running this strategy. Organic Carbon use can cause an intense bacterial bloom in the water column if over-dosed and especially if no UV sterilizer is present. This can lead to a reduction in Oxygen and additional aeration may be required. The system should be monitored closely if a bloom happens but typically if it does occur it will pass in 24-48 hours with little-to-no action required. Sensitive species such as shrimp and crabs can be affected during a bacterial bloom, so it is best avoided.

Activated Carbon is entirely different. Activated carbon is a granular product made of charcoal that has been burned at a very high temperature. As the name tells us, activated carbon is charcoal that is activated by exposure to high heat. Activated carbon has been around for more than 100 years. It’s best known for its ability to help treat acute poisoning by trapping toxins and other chemical poisons. But what is it exactly? Activated charcoal isn’t the kind you grill with, which may contain all sorts of chemicals and ingredients that would be harmful to your Reef Tank. Activated charcoal is processed at extremely high temperatures or treated with substances that make it porous and give it a mind-blowing amount of surface area — an estimated football field’s worth in a single teaspoon. During that process, the charcoal undergoes changes that cause it to develop internal holes, or pores. These pores are the key to the many benefits of charcoal — as they are part of the activated charcoal that traps chemicals and toxins and helps remove them from your reef tank.

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Chaetomorpha is a common type of macro algae that hobbyists will grow in the refugium chamber of their sump. As chaetomorpha grows, it takes up nutrients from the water column like ammonia, nitrate, phosphate which can than later be removed entirely from the system when you harvest the algae. This algae has value and can be sold online on ebay or you can throw it away, either way the nutrients have been removed from the system. This is true for all algae, not just chaetomorpha, but chaetomorpha can grow quickly into a nice mass and is easy to manage and harvest. 

We love algae scrubbers at Reef Chasers and would recommend them to anyone with a larger system / sump setup. We use them on just about every system. One of our favorite ones is an in-sump floating scrubber made by Santa Monica Filtration. Surf 4X. On large 1000 gallon systems, we use multiple of these.  On smaller 100-200 gallon systems perhaps only 1-2. Either way, we love that it is self contained in the sump, easy to access, easy to maintenance, and effectively grows plenty of algae!  

We have also recently started using APIS-60 and APIS-300 Algae Scrubbers. These are more expensive but feature a sliding drawer and plenty of surface area. Easy maintenance which we love. Effective control of nutrients by production of algae where we want it and only where want it -- no worry of light spill over to other chambers of the sump, or growing undesirable things in the sump.

The scrubber provides surface area for the algae to grow on, which is easily accessed and harvested or cleaned on a schedule. Water passes through the top of the scrubber and trickles down the surface area where the algae is growing, ultimately being deposited back into the sump. Most implementations involve mounting the algae scrubber above the sump. Or in the case of the aforementioned floating algae scrubbers, placed directly inside the sump.

We have also recently started experimenting with external Pax Bellum reactors with an LED light core that works in a similar way as a UV Sterilizer but instead for algae growth. We don't have results to report on this particular scrubber yet but you get the general idea which is the same behind all algae scrubbers. Promote algal growth where you want it and only where you want it, and harvest it frequently to remove nutrients from the system.

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A proper functioning skimmer (or protein fractionator) can have an awesome impact on water quality and nutrient control. The problem is, most hobbyists do not like to clean them regularly and over time without maintenance their efficacy plummets.  We recommend you use a skimmer on any tank 30gal or more and that you service at least once every 3 months. The market has some decent hang on the backs for small systems so if you are on the smaller end consider one of those.

Skimmers work by foaming up the debris and food particles to the top of a overflow collection cup. The particles ride the foam and are deposited in the cup for removal from the system before they can ever deteriorate into Ammonia->Nitrate & Phosphate. That's a great benefit for your system, but more than that, Skimmers affect the oxygenation of your water and improve your reef tanks overall pH by degassing the carbon.

You can expand the collection cup of most skimmers by getting a little creative with containers, hoses, and water sensor shut offs (detect overflow, kill power). Any implementation of a hang on the back skimmer should consider some sort of water sensor shut off and splash pan in case the cup does overflow. There are cheap sit-on-floor-pan style sensors that are sold on amazon. An example may be to drill a hole in the bottom of the collection cup and to silicone a tube in the bottom. The tube will run down to a larger collection receptacle perhaps a 1/2 gallon plastic container. A smaller hose and hole can be affixed to the 1/2 gallon container with a tube that runs down to a splash pan with a sensor which will detect water and kill power to skimmer.  This is a cheap, effective, and safe way to expand the collection cup of ANY skimmer but is especially useful for smaller tank and HOB configurations. Best recommendations would say to use 2 sensors (just in case one fails).

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Who loves filter socks?! Well, nobody, actually. We like them even less than you do to be sure considering we have 50,000 sock holders (just kidding, but we have a lot.) We have found over the years that we rather like to not use filter socks. Instead we opt for floss which is similar but less aggressive in its effect and easier for us to maintenance overall. Whichever you choose to use (or if you decide to go all-natural) they can be an effective means of improving over-all water quality and clarity.

For washing socks we recommend to soak dirty socks in a bucket of water mixed with unscented bleach, once you have enough socks soaking in the bucket to merit a trip to the washing machine, we recommend washing with an 'extra' rinse cycle. An unscented detergent may be used, or just a little more unscented bleach will be fine. After the extra rinse cycle is complete allow the socks to air dry before returning them to service.

For filter floss, once it gets too dirty that the water is starting to back up it is time tor remove the floss and toss it away. Floss is cheap and a large bag will last you quite a long time on a single system. The benefit of using floss is no bleach and no washing machine. Who has time for extra laundry anyways?!

Mat rollers are definitely a new age filtration method that we don't really use at Reef Chasers. They may be nice and remove the need for washing/maintenance of socks. The matt rolls itself over time and so each day your system is being filtered optimally. When the roll is done, toss it and insert the new roll you purchased. We don't find them overly practical in the commercial setting but would recommend a hobbyist with ample room in their sump and a large system check them out and do some more research to see if it will meet your needs.

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There are two types of Denitrator filters commonly known: Sulfur Denitrator and Carbon Dentirator. They both involve water passing slowly through a thick biological media bed and trickling back into the system at a slower/reduced rate. The design of both types is similar and their usage can be increasingly important in bare bottom system, systems lacking rocks or porous surface area for bacteria to populate, or anyone needing a little extra filtration to control their nitrates. Denitrators can sit in-sump or operate externally. There is less risk associated with an in-sump implementation for obvious reasons.

Typically they are designed using a large piece of PVC, typically 3-5", that is used as a "chamber" for filter media and made at the desired height to be air and water tight. Some implementations involve two chambers in a series. The chambers are stuffed with varying degrees of porous media for bacteria to set in on. The media chosen should be large enough to allow for water flow through without clogging. So fine particle media is not recommended. In fact, the media bed should go through various stages of different sized media such as lava rocks, gravel, ceramic media stones, and the like. The larger media should be located at the top of the chamber, or in the case of multi-chamber units, at the beginning and end, while the smaller media (and it shouldn't be too small, anyways) will be located at the bottom inner most area of the denitrator.

Water is fed in through the top of the first chamber using a 3/8 inch tubing / fitting and fed water from the sump with 800-1000gph pump. It is advisable to actually use a reasonably powered pump and to throttle it back with a control valve on the feed line, this will allow you to purge the denitrator if it gets clogged by opening the valve and forcing more in flow. Typically you will leave the valve highly restricted and restrict the flow to the smallest amount desired. Water will pass through the chambers and ultimately flows out of a 1/4" fitting at the top of the final chamber and back into the sump, or in the case of a single chamber it would flow out through a 1/4" fitting at the bottom.

What makes Sulfur Denitrators different than Carbon Denitrators?

In the case of a sulfur denitrator, the water is required to trickle very slowly indeed. We are talking drops per second rather than a continuous steady stream. So for the sulfur implementation of this filter we recommend a slower feed pump and fine tuning of the trickle back to the sump. This EXTRA slow rate of water flow makes for a very low-oxygen environment inside the trickle filter and results in the production of elemental sulfur (which stinks a lot like rotten eggs. You will know this is happening if you stick your finger under the outflow and catch a few drops and give them a sniff.

Regarding Sulfur Denitrators, famed Reef Chemist Randy Holmes-Farley notes: "Bacteria in this low oxygen environment will utilize the sulfur along with nitrate according to the following chemical equation:

2 H2O + 5 S + 6 NO3– → 3 N2 + 5 SO42- + 4 H+

The production of acid (H+) in this reactor can tend to reduce the aquarium alkalinity. It has also been suggested to pass the effluent of such a reactor through a bed of aragonite to use the acid (H+) produced to dissolve the calcium carbonate, and thereby provide calcium and alkalinity to the aquarium. While that is a fine idea, it doesn’t add much calcium and alkalinity to most aquaria.

Additionally, the acid produced will have a long term lowering effect on the alkalinity. In fact, it is double dipping on the alkalinity depletion since alkalinity is consumed when the nitrate is produced, and again when it is removed in the denitrator. So if you use a sulfur denitrator, be sure to monitor the alkalinity in the aquarium.

What makes Carbon Denitrators different than Sulfur Denitrators?

A carbon denitrator is designed in much the same way as a sulfur denitrator, however an extra fitting is added to the top of the first media chamber near where the water feed goes in. This RODI port allows Carbon to be dosed directly into the media chamber for a more localized effect. Bacteria populate on the media inside the chamber and go bonkers when the carbon is fed in. Carbon Denitrators do not require such a slow flow of water, instead a small, steady stream is desirable. Dwell time is important so we don't want water gushing out of the denitrator, but we want the stream/flow to be steady, almost like it's taking a leak!

As popular Reef Chemist Randy Holmes-Farley describes: 

"The end result is that nitrate is removed from the aquarium. The typical drawback to such a system is the need for careful control over the conditions, and the consequent complexity that often accompanies such a reactor. Note again that this process returns the alkalinity (by consuming H+) that was lost in the production of the nitrate originally. This method is similar to organic carbon dosing, but is localized inside of a reactor. Such localization can have advantages (less chance for cyanobacteria to be driven to grow more by consuming the organic), but it is a bit harder to accomplish technically than simple dosing of organics carbon to the Aquarium."

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Likely not encountered by most hobbyists, these are typically implemented for the larger systems 1000 gal+.  These work similar to sand filters on swimming pools and are a great tool for filtration on very large systems. They work by creating bacterial surface area and forcing the water through the fine media trapping/collecting detritus and food particles from within the water column to be processed by the active bacteria. Usually these filters can be backflushed just like in the case of a standard sand pool filter. Occasionally sand or bead media needs to be replaced, but overall water clarity and quality are improved greatly by their use.

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At Reef Chasers we believe in UV Sterilization! All of our systems are equipped with oversized UV's that we run 24/7 in line with the return pumps. UV Sterilization helps prevent and control fish and coral diseases, bacteria in the water column, algae blooms, and improves overall water clarity.  UV Sterilization is not a 'cure' for fish diseases like Ich, although it can help to control it to some extent. UV's can be an expensive addon to a small system and there for it is not the most important piece of equipment we recommend for the new hobbyist. Plus, UV Sterilization can often be added with relative ease later down the road. 

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GFO and Activated Carbon

At Reef Chasers, we use Activated Carbon on all of our systems and we change it out about once every 2-4 weeks. We use them in Fluidized Reactors. We also use a little GFO mixed in with our Activated Carbon about 25% to 75% to achieve phosphate control. 

GFO or Granular Ferric Oxide (also its just powdered rust!) is most commonly used in a fluidized reactor but can also be used in a fine-media bag located in a high flow area of your sump. GFO can deplete quickly, and should be changed out every 1-2 weeks, possibly longer or shorter depending on quality of water. GFO Works by binding with phosphate which is later removed from the system when the GFO is swapped out. 

Activated carbon is a granular product made of charcoal that has been burned at a very high temperature. As the name tells us, activated carbon is charcoal that is activated by exposure to high heat. Activated carbon has been around for more than 100 years. It’s best known for its ability to help treat acute poisoning by trapping toxins and other chemical poisons. But what is it exactly? Activated charcoal isn’t the kind you grill with, which may contain all sorts of chemicals and ingredients that would be harmful to your Reef Tank. Activated charcoal is processed at extremely high temperatures or treated with substances that make it porous and give it a mind-blowing amount of surface area — an estimated football field’s worth in a single teaspoon. During that process, the charcoal undergoes changes that cause it to develop internal holes, or pores. These pores are the key to the many benefits of charcoal — as they are part of the activated charcoal that traps chemicals and toxins and helps remove them from your reef tank.

Activated Carbon can impact the water clarity as well as help reduce nutrients, reduce/prevent coral allelopathy (chemical warfare) and remove unwanted chemicals from the aquarium such as oils on skin or perfumes/soaps on hands by binding to them similar to GFO. Although less likely to effect Nitrate and Phosphate directly, small effects have been noted.

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Lets us know what you think of this write up guys! Any improvements? Anything you’d like to see discussed further? Any comments, questions or concerns?! Let us know! We love talking reef.

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