A Scaleable Method for Raising Hippocampus erectus Revisited

by Gary L. Henkel



Some time ago, Dan Underwood published on seahorse.org and a couple of other places articles dealing with small versions of the round grow out tubs they use in Florida at seahorsesource.com.  much of what I am showing here comes from Dan’s publications, and from personal communication with Dan.  I in no way hold myself out to be an expert in the rearing of hippocampus erectus.  Indeed, the current batch is but my 4th attempt, but the first with this system.  Success rates?  Using a kriesel system I got twelve horses to maturity, and then none twice!  That’s when I knew I needed to change my setup.  So I began researching and reading everything I could on the topic.  I got extensive information from Pete Giwojna and his excellent ocean rider instructional course, along with numerous other online discussion groups, commercial aquarium facilities, and publish texts.

After much review, I came to realize that the kriesel systems, forcing fry off of the surface where they naturally migrate and frankly must migrate to inflate their swim bladders were not the way to go.  The concept of a circular system, with no corners, a nice even water flow, ease of cleaning, with centrally located drainage made sense to me.  but how was I going to accomplish this?  Dan’s systems were all constructed using regular sumps positioned below the “tank” for gravitational return.  But for me this was impossible.  I was really tight on space, and the only place I could put the system was on a counter top over our washer and dryer.  That countertop was already taller than average because of the height of the washer and dryer, so I couldn’t go very tall either, or I wouldn’t be able to access the bowl.  What a dilemma!

So I began to devise a plan for a “tabletop” scalable system.  it would have to be self-contained, literally a stand on its own system.  what follows is the build I created.


Dan had built his systems using very sturdy round koi show tubs, and I saw no reason to divert from this.


I chose one that is approximately 18 inches wide and 9 inches deep.  It It was drilled for a one-inch double sided bulkhead, and a one-inch diameter standpipe of pvc was cut to a height 3 inches from the height of the tub.  This pipe establishes the water height in the bowel.

A 2-inch female to female pvc pipe connector was modified with a dremel tool to create 3 ports, leaving a bottom edge approximately the height of the flange on the bulkhead.  These were covered with plastic window screen attached with pvc cement.



A piece of 2 inch pvc was cut to extend above the one-inch standpipe BUT below the height of the bowel.  In that way, it acts as an emergency overflow if the window screens on the ports should become clogged. The normal flow pattern is water intake through the port window screens, up the space between the two pipes, and then down the one-inch pipe into the sump.  If the windows get clogged, worst case scenario is the water level will rise until it reaches the height of the 2-inch pipe, in which case it will simply cascade over the top.

Everything is press fitted, except the window screen on the ports.  Some others have reported in their builds that the 2-inch connector fit perfectly over the outside edge of the one-inch bulkhead.  I was not so lucky, and had to sand down the interior of the connector to “make” it fit.  I have planned but have not started another connector with a finer mesh for reidi fry (window screen is too large for them initially).

On the bottom side, a very short piece of 1 inch pvc was cut and drilled with sidewall ports to better distribute water across the filter medium.

Looking through some online YouTube diy projects, I found a couple of folks had used small 3 drawer plastic desktop organizers as the basis for gravitational filters.  So I adapted this to my project.


I started with a small sterilite 3 drawer plastic organizer, which measures 81/2 by 71/4 inches.  I positioned it in the tub I chose to use as my sump toward one end, and centered.  After determining the best position for the tub, a one inch access hole was cut in the top of the organizer, through which the short extension of pvc from the bottom of the tub protrudes. I modified the back of the top drawer of the organizer just enough to allow that drawer to be pulled forward and not be interfered with by the pvc pipe extension.


The floor of the top drawer was perforated with numberous 3/16 holes to allow water to flow gravitationally downward, but not the walls.  Same for the 2nd drawer.  The bottom drawer was perforated on the bottom and along all walls to allow water to escape laterally and vertically into the sump.



From top to bottom, the three drawers were filled as follows:

Top drawer:

  1. Blue bonded filter media
  2. 100 micron felt media
  3. 50 micron felt media

Middle drawer:

Filled with activated carbon pellets in media bags

Bottom drawer:

Filled with ceramic biologic filtration rings.

The first two drawers are changed regularly.  The bottom is never changed.


Picture shows reusable sponge media in top drawer, but I later changed to blue bonded disposable media.


The sump:

I went through a bunch of assorted containers in evaluating what to use for a sump.  Again, I needed something the width of the tub, enough length to allow me to place my filtration gear, and still keep the height down so I could access the tub.  I finally found the answer to my prayers at our local restaurant supply store.  They had white opaque food grade heavy duty food storage tubs, and one of them was the width of the bowl, and I believe 25 inches deep, giving me room for my filtration gear and the tub placement.


Here it is with the tub in place.



Putting it all together

The 3 drawer filtration tower was placed toward the back of the sump to allow simple easy access to the equipment that would require daily maintenance.  The sump was outfitted with the following equipment:

  1. Octopus Nano protein skimmer
  2. 13 watts in sump uv filter
  3. A mini sochting oxidator was used at first, but I later changed it to the full size model.  This has peroxide added to it about every 2 weeks.
  4. A reactor filled with kaldness media.  This reactor is powered by the output of the pump from the uv. filter in an updraft pattern, i.e., water enters at the bottom and exits at the top, keeping the media in constant suspension.
  5.  I ended up with a lot of space next to the drawer filter units, and I had a lot of leftover ceramic media and also some plastic pot scrubbers from the dollar store, so I placed these in media bags lateral to the drawer tower to provide additional biologic filtration.
  6.  A fluval 2 filter to provide additional mechanical and biologic filtration.
  7. A maxi jet 400 return pump

The tub was drilled along the flange in 8 positions with very thin tie wraps daisy chained, with the last one weighted with ceramic media. I threw in a plastic plant because I had so many fry, but to my mind it disrupts the circular flow pattern.  One of the biggest challenges was adjusting flow rate.  I finally decided to use the criteria of the fastest flow rate I could use and not have fry getting pinned against the window screen.  That became more challenging as many of them learned that eventually artemia has to pass that way, they can hitch on the screen and wait for it, so I had to decide whether or not they simply hitched or were they pinned by excess flow.  Flow is substantially throttled back, even with a maxijet 400 being the source.  Lighting is provided by an inexpensive clip on reflector from Home Depot, fitted with an led daylight bulb and attached to the neighboring grow out tank.  Excess food and debris is siphoned at least daily with a small brush attached to a length of ½ inch tubing.  The water level in the sump is maintained at 7 inches and is marked as such.  After siphoning, fresh ro/di/saltwater is added back to the sump to maintain the water level and change out some water.


To date, after introducing this system, I have lost a grand total of 5 fry.  Five in total.  We are now beginning the 5th week with this batch, and have introduced both adult enriched artemia and mini Mysis, which they have begun to take.  Other than the need for more frequent siphoning of debris and addition of fresh seawater, nothing else has changed.  Protein skimmer is emptied daily, and pulls out regularly about 1-2 inches of mostly artemia and Mysis leftovers.

This is of course version 1.0.  as time goes on I’m sure other things may get incorporated.  But all in all, I’m very happy with this system.  All equipment is easy to access, up front, and takes minutes per day to maintain.  Fry are thriving and are noticeably larger than in previous kreisel attempts.  System is completely self-contained and tabletop.  And can easily be broken down for cleaning and moving if necessary.  I did place a small 6-inch step on the floor to make access for cleaning a little easier, but if this was on a typical countertop height that wouldn’t be necessary.  I am in the process of making a 2nd 2-inch pipe and connector with finer mesh for reidi fry, which also means I’m in the rotifer culturing business.  I’ll try to show my small area culture system for rotifers and micro algae when I get it assimilated.



Rev 3/31/2016