easy simple cheap free floatation tank plans – version 2b

Pratyahara Tanks is the worlds first completely open source tank manufacturer. Our tank is constructed from 100% off-the-shelf parts. Building this tank requires very little carpentry skills – to build a pratyahara tank is simple.

Black Beauty


  1. 2 360 gallon containment tanks – one will hold the water, one will serve as the top of your tank
  2. A large number of parts listed in my amazon store. I also recommend Doctors Foster and Smith because of their excellent 100% money back return policies, technical expertise, and low prices on next-day Saturday delivery. The next best place for online purchases is Salty Supply because they will refund even wet purchases but with a fairly hefty return fee (some refund is better than none).
  3. A hydrometer which reads specific gravity from 1.0 to 2.0. I like the one from WVR, but you need to call them to order since you’re a little guy/gal. It’s calibrated for 60 deg F, but that’s close enough for our work. You also will need to get the cylinder to hold the hydrometer, which they should have also. Dont get standard aquarium hydrometers because those saltwater tanks only have a spec grav of 1.025.
  4. 7 pieces of plywood
  5. 2-inch thick styrofoam
  6. A pump/filter system. I recommend my setup based on Lifegard Aquatics products, but you can fish around.
  7. 2 inflexible rods – used to prop up the tank top while adding salt. pvc or hard wood dowels 4 1/2 feet long are good – picture … this is during your build phase. Ultimately you want to attach drawer guides (glides) between the bottom and top tank so you can slide it top as shown in this picture
  8. a hydrometer to measure salinity of the water. I suggest the VWR Precision Specific Gravity Hydrometer with specific gravity range 1.240 to 1.310


  1. The base of your tank is a tarp, some 2x4s and 2 inch thick styrofoam – picture
  2. Then you put down one containment tank
  3. Then place the 2 aquarium heaters in the back of the tank (towards the part where you plan for your feet to be). I would suggest that all electrical outlets be protected against ground fault.
  4. Then place the pondmaster pump/filter just in front of those heaters
  5. Put the 2nd containment tank on top of the first – picture
  6. Drill holes in both tanks and slide a cinch through the holes to make your hinged door – picture , picture 2
  7. Fill the tank: start with just a few inches of water, enough to cover the heaters. Let that get up to 94 deg F, making use of an external thermometer as reference point. Then add more and more water. But never more than 250 gallons total. See the calculations for how to convert inches of water into total gallons as a function of the tank dimensions.
  8. Salt the water. Slowly. 1 bag at a time, with advice from ask floattalk to help you.
  9. Unplug all electricity and float


The Tank Room

A nice tank room that can be comfortably heated is wonderful. Here are other things to consider about the room itself.


Here is a formula:

watts / volts = amps

since most houses are 120 volts and 15 amps, this implies that you can pull at most 1800 watts of power. So buying 2 1000 watt aquarium heaters is not going to work with standard setups: I know, I threw my fuse breaker when I tried. I have 1 1k watt and another at 300 watts and so far that is fine.

You could re-wire the power from the breaker to the power supply with a different guage wire, or get dedicated wiring, but the purpose of this project is to make everything work with off-the-shelf standard parts and settings.


3 feet longer and wider than the tank seems to be an absolute minimum


A restroom near/attached to the tank room is very convenient.


Get two 360 gallon containment tanks from NTOTankOutlet.

Tank Framework

Lay down a tarp

You need to get the tank off the floor with some 2x4s. And then put 2-inch styrofoam over that. A floattalk thread discusses this in detail.

Next, simply put the two containment tanks on top of each other like this:

Then drill holes in one side and cinch the top to the bottom on one side to create a hinge like this:

I actually think padlocks are better than plastic cinches because you will find yourself taking them off and on to situate the heaters and also when you drain the tank for cleaning you will need to take off the top. Finally, some people are claustrophobic and would prefer to float without a top.

Spa Pack (pump/filter)

In order to filter the water and warm it, you could get an electronic spa pack from a place like SpaGuts.com but you will need dedicated wiring for that.  Instead, we have to go with a sealess mag drive pump and filter modules.

I’ve found 2 good choices (LifeGard Aquatics and Pondmaster) and I went with pondmaster


Here’s the data sheet and here’s your link to Foster’s and Smith. And where would we be without me trying to get a commission with an amazon link:

LifeGard Aquatics

  • we want a sealless magdrive pump that can deal with 350 gallons of saltwater (though we will only have 250)
  • we a triple capacity mechanical filter for particle filtering
  • we want a triple capacity chemical filter that has carbon in it
  • ultraviolet filtering is loved by some professionals. others think it is a waste of time
  • ozone in a closed space will kill a lot, but might also kill you. So let’s drop that also.
  • hydrogen peroxide will become a good friend of ours
  • weekly and monthly sanitization tips are forthcoming

Temperature Control & Monitoring

Water Thermometer

Submersible Aquarium Heater

In between floats, you need to keep the water warm or the epsom salt will precipitate. So you need a good aquarium heater for that. While 300W is just fine for 300 gallons when you speak of waterbed heaters, my experience is that it is not enough when dealing with aquarium heaters. You need 3-6 watts for every gallon of water you want to heat above 80 deg F. Let’s use 6 watts since we have salt water, whose specific heat capacity is lower than plain water. But on the other hand, you can only have about 1800 watts of total heating at the max. I suggest 1300 to 1600 watts of total heating power. So you’re going to need two 800 watt heaters, one 800 and one 500 or one 1000 and and 300/500 or some combination like that.

Now, there are 7.5 gallons of water in a cubic foot. And so we have the various gallons of water that we can deal with based on total wattage:

  • 1300 watts => 216 gallons of water
  • 1500 watts => 250 gallons
  • 1600 watts => 266 gallons

Epsom Salt

Crop Production Services (sometimes aka Agricultural Garden Supply) is a good place for salt. Look for a place that sells lawn fertilizers. And be sure to check floattalk.

Then setup your spa pack for intake and discharge by adding some piping.

Then heat the water to 104F (the maximum the spa pack is legally allowed to do) and gradually add salt.

Testing for Salinity

You can get fancy and buy a salinity pen, but you can also get the job done for just 10 bucks with these two products:

Filling the tank

First, start with about 3 inches of water. NO SALT. Then submerge your two heaters. Make sure you can get that up to 95 degrees.

Your maximum height is based on how many gallons of water you can heat. Let’s say you can heat 1500 gallons of water. Since there are 7.5 gallons of water in a cubic foot, we can use unit cancellation mathematics to see who many cubic feet of water we can heat:

(1 ft^3 / 7.5 gal) x 250 gal = 33 ft^3

Now the tank we have it quite wide, so the water will not be very high. Let’s convert cubic feet to inches and see how many cubic inches we can afford to heat. 33 cubic feet is 57,024 cubic inches. Now the tank slopes, but the given width and length are 93″ and 69″. So let’s multiply those together and divide that product by 57,024 to get the height available to us. The result is 8.8 inches. Most people recommend 10 inches, but I think we can get by.

Let’s do the 1300 watt calcs

216 gallons is covered by 28.8 ft^3

1 ft^3 = (12 inches)^3 = 1728 inches cubed

therefore 28.8 ft^3 is 49766 inches

So we have 7.75 inches of water available at 1300 watts. That’s not very high. I’ve done it, but dont recommend it.

General Comments


Foster and Smith Aquatics has an excellent return policy and incredible rates for next-day delivery on Saturday (and boy do they deliver!). When you are experimenting, you want a company that doesnt make bones with you when returning/exchanging/returning things.

Total cost

  • two containment tanks: 655 + 190 S&H = 850
  • spa pack with mechanical filter, no ozone: 400 + 50 S&H = 450
  • submersible aquarium heaters – 360 + 9  S&H = 370
  • water thermometer – 8.00 + 7 S&H = 15

The total cost is 1700.00. Most tanks will run you 2000-3500 used. Then we can add in epsom salt for 300 bucks for a clean 2 grand for the whole deal!

Optional Products

You might want a shockbuster, although you will probably opt to float with all heater power off:

30 Responses to “easy simple cheap free floatation tank plans – version 2b”

  1. […] http://www.thedeepself.org/2011/03/version-2b/ […]

  2. Why did you use 2x4s under your tank?

  3. well I wanted it up off the ground because most heat is lost from the bottom of the tank.

    also I was experimenting with putting waterbed heaters under the tank.

  4. Dude!

    Awesome jcl4ever.

    Have been trying to figure out how to do an outdoor tank forever, and had come up with a containment tank scenario just a few days ago.

    Came across while doing some searches.

    Big Props.


  5. Does it it drip at the top from moisture in air?

  6. Yes – but John Lilly had positive things to say about condensation dripping. I forget what he called it. I think he said it was a ‘coincidence event’ or something. I will ask on http://www.WeFloat.net

  7. I’ve asked about that here –

  8. you use the hydrogen peroxide for??

  9. water sanitation is what the hydrogen peroxide is used for 🙂

  10. Hi, if you don’t mind me asking, what is your average electrical bill for using the tank? does it cost a fortune to heat?

  11. Hi John. I use 2 aquarium heaters that use a little under 1500 watts (if my memory serves me). I didnt notice a large electric bill… I was living in Florida when I built this and just paid my bill every month… I cant give you exact numbers.

    You can ask about power consumption at http://www.WeFloat.net … they will be happy to give you some figures.

  12. thank you for your response jcl. my father is a plumbing contractor, so i have access to industrial tools and am pretty knowledgable about plumbing. so i know i can do this. biggest questions/concerns i have: .which style to build, the one with the two industrial tanks sandwiched together that opens like a tanning bed or the long rectangular ones made of wood and lined with plastic with the opening in the front. and the other worry is the cost of upkeep (electricity, salt, etc). but if the cost of maintenance is minimal, i’m doing it! thank you 🙂

  13. You are welcome. Upkeep is minimal. Of course depending on whether you are running a high-volume commercia l center or a home center. I found I needed a bit more salt every 2-3 months.

    Feel free to inquire about DIY tanks on the Social site WeFloat.net or the mailing List Floattalk, both linked to in the BLOGROLL section of this website.

  14. Hi, can u give me an example, how to hook up the filtering system. thanks!

  15. The filtering system would be manually moved up to the tank. You would simply raise the top of put in the piping and run the pump/filter. I never had my tank long enough to need the pump/filter. But the final one I build will use that.

  16. I’ve been thinking about this for years, and I like the fact that your plans have rectangular tanks, as opposed to oval ones like floattankplans.com which I paid for and wasn’t that blown away with. They do have a lot of plumbing/heating info though…

    In any case, I am going to build a tank very soon but have a question:

    First, I am building it in a not extremely insulated shed, that is really a 1500sq ft building next to my house that I use for tool storage, trailer, etc. It’s build like a house but not insulation. I’m wondering if I should take the room it is going to be housed in, inside the shed, and insulate it. Or, just insulate the tank itself better? This is my biggest concern.

  17. Hello,

    Great plans! It’s helping me a lot!

    How much epsom salt should I use for 250 gallon of water?

    Can I replace the epsom salt by another type of salt?


  18. Luiz, I do not remember. I think 800 to 1000 pounds should do it, but I have forgotten.

  19. Thanks JCL!

    Do you know if can I replace the epsom salt by another type of salt?

  20. You’re welcome Luiz. People have experimented with plain salt, but it burns your skin much easier.

    The best resource for general questions about floatation is http://www.WeFloat.net

    Are you interested in building this tank? There is now a new tank available for the same price of $2,000…

  21. Thanks again JCL,

    Nice link for resource!

    I’m from Brazil and I’m trying to build a tank here.

    The tank was easy, I bought a vinyl pool.

    Now I’m studying how to heat it.

  22. Hehe, sorry about the World Cup. I think Scolari fielded a young inexperienced team – he never should’ve passed over Ronaldinho.

    You just need to get the heaters I describe in these tank plans… but it’s better to put hot water in the tank or just heat a little water at a time, because it is very hard and takes a long time to heat 10 inches of water.

    And dont put salt in the water until the water is hot. It is harder to heat salt water than normal water.

    Do you have any pictures of your vinyl pool?

  23. JCL,

    Don’t worry about World Cup. Maybe next time!

    My vinil pool is same this one: http://mlb-s2-p.mlstatic.com/piscina-2000-litros-mor-standard-estrutura-aco-211x164x58-cm-8865-MLB20008902140_112013-F.jpg

  24. The total cost is 1700.00. Most tanks will run you 2000-3500 used. Somehow I think most people would rather pay 300 more…

  25. This looks like an excellent, and simple design. Do you have more pictures?

  26. Thank you Robert. They should be viewable using this link – https://plus.google.com/+TerrenceBrannon/posts/hFkUKU1bsgP

    or this link – https://goo.gl/photos/7VXDLk4nQL8wrd2p8

  27. Where do you suggest buy salt. I’m a few years late to the post, but $300 isn’t close to the prices I’ve found.

  28. Hi, I like using Crop Production Services. I used them in Columbus, OH as well as South Florida. They have a lot of branches – http://www.cpsagu.com/find-location

    You can also ask on http://wefloat.net/

  29. Thank you

  30. […] to The Deep Self’s DIY float tank, you will need the […]

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