Procedures for filing a float tank with salt and water – DSP 19

Graham and Ashkahn share their expertise on the nuances of filling a float tank; how much salt to use, how long it takes, and what to expect during this process with your equipment. After all, who hasn’t wondered whether their mechanical drive filtration pump can handle epsom salt filled water?

FTS Blog – How to Drain and Fill a Float Tank

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Transcription of this episode… (in case you prefer reading)

Graham: Alright, so today is another one of those relatively basic questions: How long does it take to fill a float tank for the first time and have it ready for people to float?

Ashkahn: Okay. Well, it depends on the float tank a little bit.

Graham: Absolutely, and the process that you’re going through, and your grit and determination as well.

Ashkahn: Yeah, your sheer willpower. So probably the biggest thing that makes a difference on time is whether or not your float tank has an in line heater, also called circulation heaters. For those of you who don’t know, float tanks are heated through a few different methods, whether they have a heating pad or some sort of heating system under the tub or around the sides of the tub or in the walls or something that’s heating the water and the air. The other method is where you actually have a part of your filtration system and there’s a chunk of pipe that is the heater. It’s a metal tube that has a heating coil inside of it that gets really hot and, as the water passes by, it heats it up.

Graham: And heats it up really fast.

Ashkahn: Real fast. I mean, it makes sense. It is way more efficient, right? You literally have a heating coil directly in the water you’re trying to heat versus trying to have a heating pad heat through fiberglass, which is a natural insulator, and it eventually gets its way into the water.

Graham: Yep, or even through a liner too. It would still take quite a while to heat up. So let’s do the slower process first. Let’s say that they’re filling up a tank and all it has is under tank heaters. There’s no special process for heating up the water, other than whatever is coming out of their water heater.

Ashkahn: Right. That’s where it starts. You really want to be using water that’s as hot as possible, and that’s just because the process of the salts dissolving sucks heat out of the water. It’s an endothermic reaction and actually makes the water colder. It’s kind of crazy, you can take a clump of salt and pour hot water into it and by the time it hits your hand, going through all the salt it would be cold. Or if you have salt in the tank and you’re stirring it with your hand, you just feel pockets of cold water around your hand as you’re stirring it.

Graham: It’s always the thing that I say whenever people ask if we dump the float water in between every single person. I mean it would take, in this case, probably a good eighteen hours to fill the tank?

Ashkahn: Eight to twelve, usually. If you’re diligent and you do it in this hardcore way. For us, that means we will fill it with as much hot water from our hot water heater as we can. It actually pays off to wait for your water heater to heat more hot water up — faster putting cold water into the float tank. It just makes the process of dissolving the salt more difficult too.

At a certain point the saturation point of the salt differs based off the temperature. The colder the water is, the less salt you’re going to be able to dissolve in it. Unless you’re at that ninety-three, ninety-four degree float tank water, you’re not even gonna be able to dissolve the full amount of salt you need to in there. If you’re trying to mix salt in the cold water, it’s just not gonna work. You won’t even, at a certain point, be able to mix it in and certainly will mix in less easily. It’s kind of like trying to mix sugar into iced tea versus hot tea.  

Graham: Yep, and so there’s also this process when you’re filling it up of kind of doing it — we do it directly into the float tanks. Some people will pre-mix water into buckets and mix it up that way.

Ashkahn: Yeah, it’s pretty intense though.

Graham: It’s a little bit of an intense process. Again, to each their own. Manufacturers will also have different recommendations for your specific float tank. Be sure to check with them. Some don’t seem to care if salt gets sucked into their pump and they’re running the pump the entire time, even when salt is dissolving. Other manufacturers want you to have the salt all mixed up in the water before you’re running the pump system.

Ashkahn: Yeah, and I don’t think any pump manufacturer is gonna tell you that’s great for the pump, to have salt crystals shooting through it. To me, it’s worth it … We’ve had pumps for a while … I mean, magnetically driven pumps that … I don’t really notice a lot of salt damage on them. If this pump was gonna last us ten years and, because we’re constantly using it to mix salt it lasts us nine years, to me that’s a fine pay off. I’m happy to have a pump that lasts one less year if that means I get to kick it on and help me mix the salt and water around much more vigorously than I can do by myself.

Graham: Yeah, and that being said, definitely be careful with it. Especially if you have a mechanical pump and not a magnetic pump. I would be a little cautious, or at least follow your manufacturer’s’ recommendations.

Ashkahn: In this method — putting in hot water, adding salt, mixing it up, adding more hot water, adding more salt, and just going back and forth like that as you fill it up — it usually takes us two, three, or maybe four hours to actually mix everything in. The other eight to twelve hours  is just spent waiting for the water to get back up to temperature.

Graham: Yeah, and it totally depends on the heaters too, whether you have fiberglass layers between there or you’re going straight through a liner. The entire process can take varying degrees of time, increasing anywhere from one degree an hour to a couple degrees an hour. The pace can be as low as half a degree an hour, depending on the type of heating inside your tank.

Ashkahn: However, if you have one of those inline heaters it tends to go a lot faster. With those, you’re heating the water up way faster. It dissolves the salt faster, gets up to temperature faster — the whole process is decently improved by having an inline heater.

Graham: Yep. So again, it’s that same three or four hours to actually get everything in there, mix it together, make sure that your water level is actually up to the point where the pumps can suck it in, things like that. And then probably another couple hours, I would say, running the pumps.

Ashkahn: Maybe even slightly less. They’re pretty efficient and powerful.

Graham: Yeah, so maybe in the five hour range?

Ashkahn: Yeah, that sounds right, I guess. Four.

Graham: This is something that manufacturers are aware of, too. A lot of manufacturers are making their tanks with the intention of trying to make it easier and quicker to fill them up and get them up to temperature.

Ashkahn: Yeah, these are getting better, for sure.

Graham: You’re actually seeing this combination of, almost for this specific reason, inline heaters and under tank heaters. Once you have the water all filled up, the inline heaters are good in case there is an emergency and you need to bring things up to temp real quick.

Ashkahn: They’ll save you some energy, and they help in between floats to take a little of the work off the under the tank heaters — this is certainly one of their super powers.

Graham: Which is really nice. So there you have it, kind of fumbling through that one. If it’s your first time filling this up, it will definitely take you a little longer so I definitely recommend planning on an entire day to actually set aside to get the hang of this and learn the ropes.

Ashkahn: It’s really much less of an exact science than you’d think. You might think it’s like, “Add 327 pounds of salt. Step one.” And then, “Put in 62 gallons of water.”

Graham: Like a baking recipe.

Ashkahn: Yeah, it’s really not. You just kind of dump it all in there and slowly hone in on the right specific gravity and you can be way more haphazard with it and it’s fine. It’ll get you there and there’s really not much of an actual science to it.

Graham: One thing to watch out for when you’re doing this, as well, is salt collecting on the bottom of your tank and you not mixing that in appropriately and letting it sit there  (if you have under tank heaters). What will happen is that salt will gather right over the heaters. Salt is basically a big heat sink and all the heat that wants to go into your water is instead going straight into your salt. It’s crazy, it’ll actually harden on the bottom of your float tanks and turn into, basically, big crystalline sheets. You can feel your water and it’s still just icy cold and you feel the bottom where there’s these salt sheets and it’s incredibly hot because it’s sucking up all of the heat.

Especially in something like a linered tank system, these things get really sharp and I get scared about ripping liners. You can burn out your heaters in a case like that because the heaters don’t want to be tossing all of their heat into this already hot body. It can cause a lot of problems. One thing to be really adamant about, or diligent about, during those first few hours when you’re mixing everything together, is making sure that stuff isn’t collecting on the bottom that’s really getting mixed around, that you’re doing your part to help that salt dissolve and mix up.

Ashkahn: Excellent. Hopefully that’ll help you out.

Graham: Yeah, good luck with filling your tank. We also have a great Float Tank Solutions blog post that kind of walks you step by step through the process that we use.

Ashkahn: Start by adding 327 pounds of salt.

Graham: Until then.

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