Undergravel Filterplate Filter

The undergravel filterplate filter is a great choice for you if you don’t know how deeply you want to get into saltwater aquariums. It operates on a simple principle and there are very few parts. You can even make one yourself from readily available parts. But the downside is that it can’t filter larger tanks with lots of fish.

Undergravel Filterplate

There’s a small plate buried by substrate. In the corner, there’s a tube that draws water up by blowing bubbles. As the water rises in this tube, water from the tank is drawn through the substrate to the undergravel filterplate.

Because of bacteria that lives in the substrate, this filtration system constantly draws water through the bacteria so it can process toxins in the water like ammonia, nitrite, and nitrate.

Flow rate is determine by the number of tubes you have and the power of the pump that generate the bubbles.

This type of filter will be your least expensive and most beginner aquarium owners use this. If all you want to do is keep a few hardy fish like damsel fish and not upgrade, then an undergravel filterplate filter is a great choice.

Undergravel Filterplate Limitations

An undergravel filterplate filter, by itself, isn’t suitable for every type of saltwater aquarium (as you probably guessed).

The primary limitation is that it can’t handle a lot of fish. The undergravel filter’s effectiveness will always be limited by the amount of surface area you have in your tank. So if you add more fish, you can’t make the undergravel filterplate any more effective.

In other words, you really don’t have much of an upgrade path. The only thing you can do is add more tubes and airstones. However, because they’re limited by the surface area, they increasingly become less effective as you add more.

You have to carefully control the number of fish you add to the tank or you run the risk of maxing out your filtration system (and your fish dying). A good rule of thumb is 1 inch of fish per 5 gallons.

Another limitation is the oxygen. Bacteria use up a lot of oxygen quickly and they can quickly strip the water of all the oxygen. Ideally, you should have 7-8 ppm of oxygen dissolved in the water.

The primary way oxygen enters your saltwater tank is through aeration between the air and your aquarium water surface. The bubbles in contact with the water help introduce some oxygen into your saltwater aquarium but not much.

The greater the load is in your tank, bacteria strip more oxygen from your water, leaving less for your fish.

Undergravel Filterplate Maintenance

Although this is a really simple setup, it still requires some maintenance.

Because salt will clog up airstones that produce the bubbles, you have to observe the quality of bubbles and change the airstone periodically.

Along the same lines, the tubes will eventually clog with salt residue. You will need to either clean or replace the tubing when this happens.

Canister filters are designed to handle a greater flow of water than hang-on filters and are a great choice for larger tanks. They are capable of providing 3 stage filtration:

• Mechanical
• Chemical
• Biological

Although they can and do filter biologically, they lack sufficient chamber space to hold sufficient biological media. You should use them with other biological filters.

One advantage of the canister filter is their versatility. You have the choice of customizing them to your aquarium by loading different filter media (micron pleat cartridges, sponges, poly filters, etc.). Keep in mind that the more filters you add, the more they’re going to reduce your flow of water through your filtration system.

Some people use the canister filters by themselves but you also have the option of using them in parallel or chaining them to other filtration units.

Although some canister filters are small enough to hang on the side of aquariums, most are large enough that they need to be stored under the aquarium. However, storing the filtration unit below the aquarium poses issues in pumping the water back up to the aquarium (also known as ‘head pressure’). This distance can severely inhibit flow.

The canister filters are the workhorse for most saltwater aquarium hobbyists because they strike a nice balance between cost and performance. And their size and capability makes them appropriate for most aquariums.

Choosing The Right Canister Filter

Like many aquarium equipment, you should buy the largest filter you can afford. For the most part, you can’t overfilter your aquarium and it’s better to grow into a filtration system rather than suffer growing pains.

1. Flow Rate
   This is measured by gallons per hour and the manufacturer usually gives this information on the product manual or packaging. However, they make assumptions that may not be necessarily true for your aquarium setup.
   • Head Pressure
     They assume that the unit will be level to your aquarium water level but if you keep the canister filter below in your aquarium furniture, the power to pump the water back up to the aquarium reduces flow.
   • Filters
     The manufacturer assumes you only have the standard filters installed but the more you have, the more it reduces flow.

   I recommend having enough flow to filter your aquarium water 6-10 times per hour. Click here to learn how to measure or estimate this for your aquarium.

2. Functionality
   Make sure your canister filter can take all the filters you’re looking for. Some of the smaller ones will lack the ability to take numerous filters.

Canister Filter Maintenance

• Make sure you can easily get to your canister filter. Otherwise, you’re less likely to clean it or change the filters.
• If the manufacturer sells any tools to make your job easier (or drier), buy it. If you neglect maintenance, your saltwater aquarium will suffer and the easier maintenance is, the more likely you’re going to do it.
• Purchase extra filters and keep a reserve supply. Some filters can be reused if cleaned and prepared. However, having extra filters on hand and just swapping out new filters takes minutes and makes maintenance a snap.
• Having dirty filters impede the water flow and are less effective than clean filters. Change them once a week.
• Because of salts, organics, calcium, and other debris, you should take apart and clean the filtration unit at least once a month, including hoses.

Red Mango Plant

Mangrove plants have an amazing ability to remove nitrates, phosphates, and organics. Their ability to remove organics is so dramatic, some people find their protein skimmers are hardly working with mangroves present.

As people are looking for more natural look to their saltwater aquarium, mangrove plants become more attractive.

Mangroves have natural abilities to live in saltwater. Their root system pores are so tiny, they act as natural reverse osmosis and deionization systems. Mangroves can filter up to 90% of the salt before entering the roots. In addition, mangrove plants have some of the most effective salt secreting glands on their leaves.

They use the nitrates, phosphates, and organics as nutrients and they need them to grow.

If buying mangrove plants from the Internet, be sure to check whether it’s legal to own them. Florida considers them protected species while Hawaii considers them weeds. Other places will have their own laws.

If you decide to introduce mangroves to your saltwater aquarium, you can get them in one of four stages:

• Seeds with no roots
• Seeds with the start of a root system but no leaves
• Seedlings with some roots and leaves
• Seedlings with fully developed roots and leaves

Red Mango Plant

Mangroves are one of the few species of plants that actually germinate while on the parent plant (although they can germinate while detached). By the time a seed naturally detaches from its parent, it may be up to 3 feet long and have a developed root and leaf system.

The earlier in the life stage you get mangroves, the more time it’ll take to mature and see results. But it’ll also be less expensive.

Probably your best source of mangrove plants will either be local nurseries or fish shops.

Mangrove Care

Mangroves can grow like weeds, if you use VHO bulbs (Very High Output). Some people report trimming leaves and roots weekly with VHO. If you buy Mangrove seeds, you may want to use VHO bulbs to initially grow them but cut back when they’re mature.

Mangroves depend on water currents to expose them to nutrients. Your aquarium should have some way to produce currents to ‘feed’ the mangroves.

Be sure your aquarium produces enough nitrates and organics to provide enough nutrients. If not, you may have to overfeed your tank to produce enough nitrates for them to survive.

Mail Order Mangrove Plants

The mangrove plants will come in a box and has probably been traveling for a few days. It hasn’t had carbon dioxide (plant equivalent to oxygen) or been exposed to light for all that time.

One of the worst things you can do is immediately plunk it down into your aquarium. You have to take time to acclimate it properly. Sometimes the mangrove is so shocked, it can go into a dormant stage.

Remove the mangrove from the packaging, gently rinse the entire plant with fresh water, preferably room temperature.

Mangrove Placement

The funny thing is that you don’t have to put mangroves into the aquarium. Some people actually keep them in the sump or filtration system. As long as they’re put someplace where the water flows, they’ll do their job. But some pepole do like putting them directly into their aquarium.

If you bought mangrove seeds, you float them in tiny bits of syrofoam, making sure the seed is in contact with the water. Roots will start to develop first to anchor them and then the leaves.

If your seedlings already have roots and leaves, position your mangrove plant so that the roots are below the water and the leaves are above the lights. Mangroves can and do grow with ambient light but for the first few days or weeks, it’s best to keep them from too much light.

2 mangrove plants per 30 gallon should be a good balance.

Red Mangrove

Red mangroves are one of two common species used for saltwater tanks. They are quite hardy and can survive in dormancy in the water up to a year. However, once activated, they’ll quickly grow roots.

One thing that’ll astonish you is the rate the roots grow. In the wild, mangroves need to anchor themselves quickly to survive.

They tend to be longer of body than the white mangrove and they’re a better choice for deep tanks.

White Mangrove

White Mangrove Seed

Their roots grow faster than red mangroves and they tend to be shorter. They’ll also develop more hair roots than the red mangrove. They’re a better choice for shallower tanks.

For marine or saltwater aquarium tanks, protein skimmers (also known as foam fractionating) is important to your marine or saltwater aquarium health. A protein skimmer will remove organic material (like excess food particles or feces) before it breaks down into ammonia and interrupt the nitrogen cycle. It also can remove trace minerals like copper, which is lethal to most invertebrates.

All protein skimmers work on the same principle but the designs vary widely (and the cost as well). Bubbles are blown through the water and organic material attaches itself to the surface through surface tension. At the surface, the organic material is collected or “skimmed” into a cup and you dispose of the contents.

One factor in protein skimmer effectiveness is the ‘dwell time’. It basically measures how long a bubble is in contact with the water. The longer the dwell time, the more chance organic particles have to attach to the bubble.

Another way is to decrease the size of the bubbles. This produces more bubbles per cubic inch and produces more surface area.

Because of the size requirements, a lot of protein skimmers are kept in the aquarium stand but some of the smaller units are hung in the back.

Protein skimmers are more important for fish-only tanks than reef aquariums. A reef aquarium has coral, live plants, and invertebrates that process nitrates whereas a fish-only tank does not.

Co-Current Protein Skimmer

Co-Current Protein Skimmer

Water is pumped through a plastic column. Air is pumped to the bottom of the column and is commonly expelled through an air stone (a piece of limestone or wood that produces tiny bubbles).

As the bubble reaches the surface, it bursts and releases the organics. As the organics collect, it foams and the foam is skimmed into a collection cup for disposal.

The water enters the column from the bottom, runs parallel to the bubbles, and exits at the top either back into the aquarium or to another filtration system.

Ideally, the column should be milky white with bubbles but as the salts and other minerals clog the air stone, they need to be replaced periodically.

This is the simplest and earliest design (and the least expensive). It’s usually anywhere from 6′ to 18′ and can be mounted behind the aquarium. It’s also great for tanks 30 gallons and below.

Counter-Current Protein Skimmer

Counter-Current Protein Skimmer

This design is exactly the same as the co-current protein skimmer except the water enters at the top of the column, runs against the path of the bubbles, and exits at the bottom of the column.

By running against the direction of bubbles, it increases the dwell time and increases effectiveness, without increasing the size of the unit.

This desing probably has the greatest variance in design. It can be small enough to hang at the back of the aquarium tank or large enough that it needs to be kept below in the aquarium stand. It’s appropriate for tanks from 30-75 gallons.

This is the hobbyist-grade protein skimmer and will meet the needs of most people.

Venturi Protein Skimmer

Venturi Protein Skimmer

The venturi protein skimmer depends on high water flow to create vortexes and eddies in the column of bubbles. This increases the dwell time and the effectiveness of the protein skimmer dramatically.

However, because this type of protein skimmer depends on high water flow, you will need a stronger pump than the other types to produce this flow.

Some design rely on an air stone to produce tiny bubbles. Others run the water horizontally through a nozzle and across an intake valve exposed to air. The high speed of the water naturally draws air in and produces bubbles.

This will be your most expensive option but also your most effective mechanical option.

Final Thoughts

Now not all protein skimmer will fall neatly into these categories. There’s going to be some crossover and improvements but this should give you a broad overview of what to expect.

Before getting a protein skimmer, decide if you need one. If your nitrate readings are consistenly low (under 10 ppm), you don’t need one. If you see high nitrate readings, take several over a few days to make sure it’s not a temporary spike.

If you decide to purchase a protein skimmer, get the best or biggest you can afford. Like picking a good saltwater aquarium tank, making several upgrades can be expensive.

Also, there are other options to control nitrates like other live rocks or live plants. Keeping mangroves, for example, not only filter unwanted nitrates but phosphates as well. And they due to their root system, they can survive in saltwater.

Hang On Filter

A hang-on filter is external to the aquarium and hangs on the side or back. There’s an intake tube that runs deep into the aquarium and a motor that draws water into the filter. The water is then run through various filters before being returned to the aquarium tank.

Advantages:

• It can filter mechanically, chemically, and biologically
• Because the motor is small, it’s a very quiet filter
• It’s probably going to be the least expensive of your options

Disadvantages:

• Due to the design, it cannot meet the needs of large tanks without other systems (i.e. protein skimmers, denitrator coils, refugium, etc.)
• Frequent maintenance will disrupt necessary bacteria colonies.

Commonly, the water is drawn from the intake tube to foam pad of some type. This traps uneaten food, plant matter, waste, and other debris. This step will remove the largest particles. This is the mechanical filtration.

Just a note, make sure your intake tube has a grill or vent to prevent fish from being sucked in. I kept a tiny frog in a freshwater tank and one day, it disappeared. It baffled me until I cleaned out my filter and I saw bits of the frog.

Next the water is run through a filter bag, often containing activated carbon. The carbon binds with toxins and pulls the organic wastes from the water. This is the chemical filtration.

Hang On Filter

Finally, bacteria forms on both the foam pad and filter bag (or activated carbon). The bacteria breaks down ammonia (a waste product of animals like carbon dioxide) into nitrite and then into nitrates, which can be used by any live plants you have in the tank.

This is a straight-forward design and is simple to understand and operate. However, you also need to provide frequent maintenance. You should rinse out the foam pad weekly of debris. Also, you need to change the filter bag once a month.

This has the unwanted side-effect of disrupting the bacteria colonies that live on the foam pads and filter bags. Although the bacteria lives in other parts of the aquarium and will eventually repopulate your filter system, this is less than ideal.

One way to get around this is not to replace all of your filter media all at once. For example, if you have a foam pad to catch large particles, cut it in half and rinse out one side at a time. If you have activated carbon bags, put the new bag with the old for a week, before disposing the old bag.

The rule of thumb for filters is more is better. When a hang-on filter reaches its limit, the next step up is the canister filter.