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Trickle Filter Systems

      Jared has tried to explain his trickle filtering system to members of the turtle list in several posts. Jared has written a short description for each picture featured below. Additional pictures and descriptions will follow in the near future.:)

      Please click on the pictures if you would like to have a better view of each photograph.

  •       This picture represents the beginning of a transition in filter design for a 180 gallon brackish water tank. The salinity was maintained at roughly 1.012 and there were approximately five sub adult malaclemys terrapin centrata in this enclosure.

    As it can be seen, there are three types of filtration:

    1. protein skimmer;
    2. external canister filter and;
    3. trickle filter.

          The protein skimmer is a standard air driven skimmer. The skimmer column is 4" in diameter, roughly 20" high and there are four wood air blocks in it. The air pump is a Wisa model 200. The Wisa was chosen for its superior design and durability. Its PSI simply cannot be matched by any of the less expensive plastic air pumps. The only plastic air pump that comes close to the Wisa in quality is the Tetra Luft air pump. At a fraction of the cost of the Wisa ($50 vs. $200) it is a very good buy for the money. The only draw back is the noise - it is significantly louder that the Wisa, and at maximum output, it can not be used on a set up that is in a public area of the house. The water is pumped into the skimmer from a submersible Eheim 1260 pump that is in the tank.

          The canister filter is a Eheim 2260. It uses the same Eheim 1060 pump that was discussed in one of the earlier pictures. While this filter is definitely superior by function and design to virtually any other canister filter, its' size makes it awkward to clean, particularly when there are heavy bio-loads, which will necessitate cleaning on a more frequent basis. The bio-media that is inside of it is made by Eheim and is a highly porous, large surface area type of synthetic stone. The problem is that is becomes easily clogged which therefore reduces the flow of water through the filter.

          I substituted this media with larger pieces of lava rock, which still did not improve matters much as the lava rock also became clogged with detritus, thereby raising nitrate and phosphate levels in the tank. As the next picture demonstrates, the canister filter was removed.

          The third type of filtration is a over the tank trickle filter. It works exactly the same as the one described in one of the pictures below. It too uses an Eheim 1060 water pump, mounted externally, which can be seen in the picture.

  •       This picture represents the final transition on this 180 gallon tank. It is an end shot showing the protein skimmer, and large custom made hang on pre-filter. Within the pre-filter, there are roughly 2 gallons of flex-rings, increasing the surface area of the bio-media.

          The blue Rubbermaid storage bin that is depicted in this picture, and in the following picture, is used as a top sump to compensate for evaporation. The frontal view of the 180 gallon tank shows the bin connected to a small section of reverse osmosis tubing (from an RO unit - though any kind of thin tubing will work). There is a small nipple that has been screwed into place at the bottom of storage bin. Silicone has been added to help ensure a water proof seal.

          The other end of the tubing is connected to a nipple that comes through the side of the trickle filter box. Inside the trickle filter box is a float switch, much like the float switch that is used in the basin of your toilet bowl. It is not electric. The two primary differences are that: it is much smaller, and it is made entirely out of plastic - there are no metal parts.

          When water evaporates from the tank it in turn affects the water level in the entire system, including the sump in the trickle filter. Therefore, when the water level in the sump in the trickle filter drops, the float switch in turn drops, which then opens up a small valve connected to the switch. When the valve opens up, water from the blue storage bin is allowed to pass through in a drop by drop fashion, thereby topping up any evaporation.

          I fill the storage bin up weekly. There tends to be greater evaporation in the winter time owing to drier air, as well as increased air circulation form the furnace. If a float switch and external top-up sump is not used, then you will have to be diligent with respect to watching for evaporation, as once the water level gets too low, the pump will start to suck air. This will not be a problem for a few hours or even an entire day. However, should you go away for a few days, your pump could easily be irreparably damaged through over heating.

  •       This shot is a frontal view of the previous picture. As it can be seen, the main filtration is a under the tank trickle filter. It is filled with plastic flex rings. The pump that is used is a Little Giant 4MDQX SC, which circulates roughly 1200 GPH. The drain from the pre-filter can also be seen, showing a stiff 1.5" PVC pipe connecting the bottom of the pre-filter to the top of the trickle filter. There is also a 1" bi-union ball valve connecting the pump to the trickle filter. The bi-union feature comes in handy when the pump needs to be removed for cleaning, or when the trickle needs to be removed. Also, is a 1" single union ball valve from the exhaust of the pump. This allows the user to reduce the water flow into the tank for any necessary reason, such as cleaning, feeding etc.

          The lighting is composed of one 175 watt, 5500 Kelvin metal halide lamp, and four, four foot 40 watt Zoo Med Reptisun 5.0 florescent lamps. All lights are on timers following the photo period of the day and the seasons.

  •       This picture represents a transition in trickle filter design and terrapin housing. After having used a 180 gallon glass tank for a few years, and watching the terrapins swim endlessly up and down the sides, I felt that perhaps a round tank would be better for their state of mind. I thought that maybe the roundness would create the illusion of an endless swimming space. Underneath the basking platform, is a internal prefilter. This prefilter is held in place with a plastic tank adapter that has been screwed into the bottom of the kiddy wading pool. To aid in forming a better water proof seal, I added quite a bit of silicone as the bottom of the pool was not perfectly flat. The trickle filter design was basically the same as the one pictured under the 180 gallon tank picture.

    The three primary differences were:

    1. The 180 gallon tank has a hang on prefilter whereas the kiddy pool is drilled with an internal prefilter;
    2. The trickle filter on the 180 gallon tank is a custom made acrylic unit filled with flex rings whereas the trickle filter on the kiddy pool was made out of two Rubbermaid containers (similar to the earlier picture, only much larger) and:
    3. The pump on the 180 gallon tank is an external Little Giant 4MDQX SC, which circulates roughly 1200 GPH whereas the pump on the kiddy pool was a Quiet One, which circulates roughly 750 GPH.

          The cost of the 180 glass tank, metal stand, trickle filter, hang-on prefilter, bio-media, pump and all of the fittings and piping was roughly $1200. The cost of the kiddy pool, home made wood stand, Rubbermaid storage bins, fittings, piping, internal prefilter, lava rock and Quiet One pump was roughly $350. The choice should be fairly obvious.

  •       This picture represents an above the tank trickle filter. As it can be seen, the trickle filter is an aquarium that has been converted into a trickle tower by siliconing another glass plate over the open side of the aquarium, and by removing one of the end plates which serves as the top. There is a (roughly) two inch space left at the bottom which allows the water to pass back into the tank. I have also added a piece of glass on either side of the opening so as to create a smaller opening that the water is channeled through.

          The bio media is standard plastic flex rings, which are resting on top of plastic egg crate, which is in turn secured inside the tower at the same height as the opening. On top of the flex rings is a piece of sponge and a drip plate, and then on top of that is some floss that can be easily discarded.

          One end of the aquarium has been removed, and has been replaced with a 3/8" thick glass plate that has a hole in the centre. In the hole, is a plastic tank adapter that is connected to the 5/8" flexible tubing from the pump. The 3/8" glass plate is the lid to the trickle filter.

          As it can be seen, the pump is supported outside the tank on a small shelf. The intake is simply constructed out of some PVC elbows and some flexible tubing. In this application, the pump is an Eheim 1060, which circulates roughly 540 GHP. For a 90 gallon tank, this is adequate. Personally, I prefer the Ehiem pumps because they are incredibly quiet, the parts are easily replaceable, and the shaft is ceramic, making it almost indestructible, it certainly offers very low resistance and is tolerant to salt water.

          For circulation, I have also added a small submersible Fluval 4 filter. In this tank, I had four ornate adult (2:2) diamond back terrapins.

  •       This picture represents the cheapest, and easily constructed trickle filter. It is made out of two Rubbermaid containers. The round one is filled with crushed coral to serve as the bio-media. The bottom of the round container is drilled with numerous small holes to allow the water to pass through. In the lid, is a 1/2" fluval elbow which holds the tubing from the pump.

          As the picture demonstrates, the return to the tank is simply a 3/4" threaded PVC elbow, with a barb that has been screwed into a hole cut in the centre of one of the ends of the rectangular Rubbermaid (the sump). Attached to the barb are a couple of Aquaclear 500 intake stems (coincidentally enough, they fit perfectly). They were attached to reduce the amount of splashing occurring in the tank with the water dropping almost one foot. Flexible tubing that fits over the barb would also work.

          This filter is ideal in emergency situations. For the set up depicted here, I had acquired a large adult female diamond back terrapin from a Chinese fish market. Not having anywhere to put the terrapin on a more permanent basis, I threw this filter together from parts that were lying around the house. The tank is a shallow 40 gallon, measuring 36"X18"X15". The pump that was used here is the second smallest Rio submersible, perfect for small application such as this one.

Any questions concerning the design and application of these filtration setups should be directed to:

  • Jared Purdy
  • 384 O'Connor Drive
  • Toronto, Ontario
  • Canada
  • M4J 2W1
  • (416) 424-1676
  • (If you would like to speak to Jared, please do not call between the hours of 10 p.m. E.S.T. and 8 a.m. E.S.T. Thank-you!)

This article was published on the internet 1997, and is the copyright © of Tricia Power and Jared Purdy. This page will be updated periodically. All rights reserved. No part of this page may be reproduced in any form without the permission of the author or the photographer. Please contact Jared Purdy or Tricia Power at the above email address if you would like to use this article for educational purposes. :)

Last updated
Mar, 19, 2010

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