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The Ragtop DIY Tank: version 2024

The ragtop DIY Tank is shown here:

Design Criteria:

  1. Inexpensive – a grand or two and you’re done with spending.
  2. Easy to build – more like “snap together, done” – no sawing, measuring, nailing and all that jazz. All you need is a drill to make a few 3/8-inch holes and some 1/4-inch zip ties. A 70-year old woman should be able to build this. of course, she could also hire a person for 1-2 hours and get the job done as well.
  3. Passive heatingno heating of the water while floating.
  4. Open Source – every aspect of tank design is publicly disclosed.

Materials List

ProductPictureAmountCostDescription
325 Gallon Poly Open Top Containment Tank (protank.com)1$60024-inch high containment tank. 8 feet long, 5 feet wide.
Tarp1 $25To open and close the tank. Tarp should be 1 or more feet longer/wider than the tank on each side
1/4″ Zip ties3$5The top of the tank is formed by running zip ties through holes in 3 sides of the tank
Drill and 3/8″ drill bit1$50You put holes in the lip of the plastic and the tarp so you can cinch it tight with zip ties.
Lifegard Aquatics Quiet One Pro Model 50001$210Spa Pack – Pump
Inland Seas Nu-Clear Model 533 Canister Filter, 25 Micron Cartridge & Carbon Filter (marineandreef.com)$250Spa pack – Filtration
Reducing Nipple 1″ x 3/4″ Polypropylene, black (marineandreef.com)1$6plumbing connection necessity
Pentair Aquatics Lifegard Aquastep Pro 25 Watt UV Sterilizer (marineandreef.com)$200Spa Pack – UV sterilization
Water Heater
H2Pro 1000 Watt Heater & IceCap Magnet Mount Package (marineandreef.com)$160Heating the water

Total Cost$1500Price does not include salt.

Simple Build/Purchase Instructions

Put down the containment tank.

Once it’s loaded with salt, it will not be moving an inch. Scrub the inside of the tank with hydrogen peroxide.

Anchor the tarp to the tank by drilling holes and zip-ties.

We need to drill holes in the plastic so that we can cinch the tarp to the tank. This video explains how to drill a hole to create an anchor point.

The previous iteration of this tank had a different location for position 3. The new location for position 3 allows for another hinge to be created.

At position 1, Put the tarp over one corner of the tank lip. Drill a 3/8-inch hole in the Northeast corner of the containment tank lip, driving the hole through the tarp as well as the plastic. Then put a 1/4-inch zip tie through the hole and tightly cinch the zip tie. Position 1 serves as the first anchor point for your tarp.

Now go to position 2 — the Southwest corner of the tank. Pull the tarp as tightly as possible. The goal is to reduce sagging in the middle of the tarp. Sagging in the middle of the tarp would lead to the tarp being on your face or body. But be careful – a tarp can tear. While holding the tarp as tightly as possible (without ripping it), drill a 3/8-inch hole in this corner of the containment tank lip, driving the hole through the tarp as well as the plastic. Then put a 1/4-inch zip tie through the hole and tightly cinch the zip tie.

Now go to position 3 and make a hole in the tank lip and the tarp and zip-tie corner 3 down as well.

Position 4 is another place where you are pulling very hard on the tarp in order to reduce tarp-sag. Position 4 forms about a 30 degree angle with the top lip of the tank with position 1 as the vertex. Position 4 cannot be too close to the northwest corner-lip of the tank: otherwise you wont be able to flap the tarp open and closed to get in and out. But if it is not close enough, then you run the risk of tarp sag. I would suggest that Position 4 be determined experientially: leave out this additional anchor point. Fill your tank with salt and heat the water and start floating. During each of your pilot floats, notice (1) how much tarp you need to open and close to enter and exit comfortably (2) where the tarp tends to sag. Then you will know where anchor point 4 needs to be based on direct experience. My anchor point 4 is 31 inches from the Northwest corner of the tank as this video shows.

Now, heat the water (AND BE CAREFUL)

To heat the water, we use a temperature controller.

BE DAMNED CAREFUL about what you plug into what. When I first got my H2O Pro, I plugged the heating element directly into the wall instead of into the temperature controller and it started heating up without limit and I almost burnt the shit out of myself. YOU HAVE BEEN WARNED. Read the f*cking instructions and make sure you do it right. Or pay a serious price.

Make sure the water heating element is at least 2 feet from the temperature probe. Otherwise you will be getting a local read of the water temperature. Some people use a wavemaker to circulate the water. I sometimes take a dowel rod and slosh the water around. But most of the time, I just make sure there is decent space between the temperature probe and the water heater. I suggest you put the temperature probe along the north wall of the tank, maybe 6 inches from position 1. I suggest the heating element be placed in the center of the tank so that it radiates heat in all directions equally (position H in the diagram). Further experimentation shows the most even heating of the water occurs with the heating element along the west wall.

Filter the Water

Marine and Reef has a beautiful pre-configured spa pack that includes pump and filtration. The filtration part includes mechanical/particle filtration, carbon filtration and UV filtration. However, the Iwaki pump they include is gravity-fed (it cannot pump water vertically only horizontally or less than horizontally) and designed to sit outside the tank. I had ZERO interest in drilling holes in plastic and hoping that water would not leak all over creation. Remember, the design goal here is easy – a grandmother could do this if she wanted to. So even though I bought their pre-configured spa pack, I needed to return the Iwaki pump and get a pump that I could submerse, the Lifegard Aquatics 5000.

Floating in the Ragtop DIY Tank

To enter the Ragtop, you perform the following steps every time:

  1. Unplug the temperature controller
  2. Open the flap.
  3. Remove the water heater from the water and put into a container that can hold a potentially hot probe. When removing it, say out loud: heater removed. The reason you say this is because during the float, you will often feel certain things as nerves discharge – you will feel tingling, electrical sensations, etc. And you will think that you accidentally left the water heater in the water. But because you said “heater removed” when removing the heating element, you can recall this and continue to float with a sense of confidence.
  4. Enter on a diagonal roughly perpendicular to the line formed from anchor points 1 and 4.
  5. Enjoy your float.
  6. To exit, move back to the Northwest corner of the tank and sit up. Your head will pop the flap up.
  7. Put your hands on the lips and stand up.
  8. Keeping contact with the railing, turn around
  9. Step out.
  10. Head to the shower. Dont worry about closing the tank or reactivating the heating system now. Simply get to the shower and enjoy the warm shower.
  11. Once done, maybe pour a bag of salt or top up the water level.
  12. Put the water heater back in the tank, well away from the temperature probe.
  13. Turn on the temperature controller.
  14. Enjoy your planetside trip until the next float.

Reflections, Commentary and Scope for Improvement

Make sure the tank you buy is NEW and in GOOD SHAPE

If the walls of the tank are warped, then that increases the chance that the tarp will not snugly fit

The height of the containment tank

In this build, the containment tank height is 24″. Contrast this with the Black Beauty where the effective height was 32″ because 2 16-inch containment tanks were stacked.

A major concern with 24″ high is the athleticism necessary to enter and exit the tank. Two feet of height presents challenges, especially when exiting.

Another concern that height presents is this: the more height there is, the more unheated air that will tend to seek homeostasis with the room temperature air.

For this reason, we would probably never use this tank from Global Industrial:

This tank is 28 inches high. Which means an additional 4 inches to clear entering and exiting the tank. That being said, the workmanship on this tank is absolutely gorgeous:

  • 2 levels of tiering within the walls
  • a nice wide generous tank lip to drill holes into

A very professional company with excellent customer service and highly useable website.

But unless someone develops an easier way to enter/exit such a tank, it has to be disqualified as too high to safely enter and exit, especially given that your feet are in water and your hands are wet.

Ideal height is probably 20 inches. But I’m having a good time with the 24 inch high tank

24 inches is a challenge to get into and get out of. I’m doing it and will continue to enjoy it. 20 inches would make those tasks easier, but more than likely the tarp will sag onto you. So unless a more clever way to keep the tarp up comes along, we are stuck with 24 inches high.

The floor of the room can be an issue

In the apartment I am in currently, the ground floor has cold floors. The black beauty was built in a mobile home with raised floors. It may be useful to elevate the tank from the floor so that bottom of the tank is not in a game of mortal combat with a cold floor.

Adding ions to the water

Fluid float has a wonderful device that adds Copper, Zinc and Silver to the water. We all know the power of sanitation that can come from these elements. If you have the extra $500, I think it makes a great addition. The Pond Guy has one as well.

Extended, continuous floating is hampered

One of the interests of the builder of this tank is extended continuous floating – floating 24/7 for days or weeks. Manually adding and removing the water heat distracts one from just floating. To mitigate this one can be mindful while reheating the water. This is just an idea.

Replace the tarp with…

Bubble wrap?!

One of the best DIY tank designs emulates a Zen Float tent. In his post, he mentions using bubble wrap to preserve water temp between float.

Pond supplies versus aquarium supplies

During this build, I became enamoured of Marine and Reef for their large inventory, expert experience and prompt support. That being said, marine and reef is an aquarium shop and floatation tanks are bigger than most aquariums.

In the area of filtration, I am using supplies designed for 150-220 gallon aquariums. Compare that with pond equipment rated to work with 5000 gallons! The Pond Guy is one of the better places for pond supplies, including filtration.

Anecdotal History

First a little history:

  1. In 2011, I built and used The Black Beauty DIY floatation tank: it used 2 containment tanks — one as the bottom and one as the top.
  2. In 2024, I built a tank that I planned to be called the White Beauty. It was intended to use 2 containment tanks just as its predecessor. But the build failed.
  3. In 2024, I then created the Ragtop DIY tank, which is described in this post. It only uses a containment tank for the bottom while it uses a “ragtop” for the top, currently a tarp. I guess necessity is the mother of invention. Here I was pissed at the company Chemical Containers for selling me warped tanks that did not fit on each other. They sent me a replacement but that one was not so good either. Plus it was way too heavy for my friend to lift. The float experience was horrible because the top was leaking room air which was at 82 deg F. In my apartment, I cannot jack up the heat to 93 deg F (one way to make up for a make a tank that is too cold above the water). I’m grateful that Lowe’s Hardware refused to accept the 16′ x 20′ tarp that I tried to return. Just as an experiment, I slapped the tarp onto the tank and ran the zip ties through the holes I had already made. And it’s been working great.

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