Cap for a Tank watch holding tank monitor.

I am going to be replacing my holding tank monitor and I currently have a Tank watch 4. I want to remove the sensors, replace the cap with a blank cap, and them eventually cut a hole in that to install a dyi aeration system. Anyone know where to get a blank cap? Is it a typical 3" ismpection port thread? It needs to seal completely.

dhays said:

I am going to be replacing my holding tank monitor and I currently have a Tank watch 4. I want to remove the sensors, replace the cap with a blank cap, and them eventually cut a hole in that to install a dyi aeration system. Anyone know where to get a blank cap? Is it a typical 3" ismpection port thread? It needs to seal completely.
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The sensors are just hollow plastic tubes. Why not just leave as is and use the “empty” sensor as the air tube.

fryedaze said:

The sensors are just hollow plastic tubes. Why not just leave as is and use the “empty” sensor as the air tube.

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I thought about it and that might be the best way to go. The sensor tubes look to be 1/2" OD polystyrene and are pretty thin-walled. I would want to be able to put a T at the bottom to spread the area that the bubbles would be exiting. I'm not terribly familiar with plastic pipe so don't know if there are T fittings that would cement to the polystyrene. I also would want to cap off the other two holes where the sensors are located. Not sure how I would do that. That might be as simple as cutting the sensor tubes off just below the cap. However, I was thinking that it would be just easier to start with a blank cap.

That cap is a 3" inspection port, Dave...and it would be a LOT easier to start with a "clean" cap. You may be able to buy just a cap and rubber o-ring (The Tankwatch has one, but for $3 or so that a rubber o-ring costs, I start with a new one 'cuz they do dry out. Check the Beckson site.



And now you're gonna need a new tank level indicator too. The Profile "solo" is inexpensive and can use the TW4 wiring. Profile Tank Monitors



--Peggie

Wow, I was going to ask the exact same question as the OP. I have installed a Profile monitor and love it but want to get rid of the old Tankwatch assembly and feel comfortable about opening and cleaning the tank. I have looked everywhere I can think of including the Beckson site but to no avail.

Ken

HeadMistress said:

And now you're gonna need a new tank level indicator too. The Profile "solo" is inexpensive and can use the TW4 wiring. Profile Tank Monitors--Peggie

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And the Solo is trouble and maintenance free. (From a happy Solo owner, formerly unhappy Tank Watch owner).

Dave maybe this is what you want, right in Seattle at Marinesan.....

HeadMistress said:

That cap is a 3" inspection port, Dave...and it would be a LOT easier to start with a "clean" cap. You may be able to buy just a cap and rubber o-ring (The Tankwatch has one, but for $3 or so that a rubber o-ring costs, I start with a new one 'cuz they do dry out. Check the Beckson site.

And now you're gonna need a new tank level indicator too. The Profile "solo" is inexpensive and can use the TW4 wiring. Profile Tank Monitors

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Thanks Peggie. I couldn't find any info on the Tankwatch site on the cap, so you confirmed my suspicion.



And yes, my plan is to install a Profile Solo with the external sensor. I think that it will work with my FRP tank. First step is to install the Profile tank monitor, and seal up the TankWatch sensor opening with hopefully a new cap. Next step is to re-route my vent line a bit as it has one low spot. Then I want to create an aeration system.

rochepoint said:

Dave maybe this is what you want, right in Seattle at Marinesan.....

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That is exactly what I want. Thanks!

rochepoint said:

Dave maybe this is what you want, right in Seattle at Marinesan.....

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That should do it. Thanks.

Ken

I have another question for the TF brain trust.

When you look at the Grocco Sweetank system, they use a length of tubing with a bunch of holes in it to create the bubbles which oxygenate the holding tank. Most of the DIY systems seem to mimic that.

However, when I look at live bait aerators, they typically use 1 or 2 bubble emitters, so that all the bubbles are concentrated in one location. Those fish seem to survive just fine.

So I’m wondering if a very simple system where the bubbles are created in a small area of the holding tank would be sufficient? It would sure be easier to make and, more important, easier to remove and maintain than another configuration. Granted, I don’t have a bunch of fish swimming around in my holding tank to mix up the water, but at least while the the boat is moving, there is going to be a lot of motion of the fluids in the holding tank. In addition, any time the head is flushed, the tank contents will be agitated to a certain extent.

So, any thoughts? I’m currently thinking of a downpipe with a small T at the bottom with two short horizontal pipes with small holes drilled in the bottom side. The idea is to make it so that the T could be lifted out of the 3” inspection port. So each leg of the T would be about 2 1/4” long.

OK, no opinions on the holes so I don’t think it matters. I picked up a bubbler from Cabela’s yesterday, Power Bubbles 12v Air Pump by Marine Metal Products. It is designed to to be used in live bait tanks. It has two air outputs that can be T’d together if you are only using 1 tank. They claim it will keep fish alive in a 35g bait tank. I figure it will keep aerobic bacteria alive in my 50g black water tank.

I spent a couple hours at Home Depot trying to figure out the appropriate adapters etc.. to connect the 1/8” ID air hose to the 3” cap pictured earlier and to some CPVC 1/2” pipe. I got a 1/2” CPVC to 1/2 MIP adapter, a 1/2 MIP to 1/4 FIP hex bushing, and a 1/4 MIP to 1/8” ID hose barb adapter. I used the 1/8” hose barb instead of a 1/4” because the 1/4” seemed a bit too big for the hose supplied with the bubbler. I epoxied the CPVC to 1/2 MIP adapter to the cap with some thickened epoxy.

Tested it in a bucket at home with the car battery and it seems to work fine. The bubbler claims to use less than .5amp and produce over 5 1/2 liters of air per minute. That is likely overkill for the holding tank so I may wire it with an electronic timer on the same circuit as my shower sump. That way it is easy to turn on and off and I can set it for as much of a duty cycle as I want with the timer.

Pictures to follow.

Here are some photos and a video of a bucket test.

https://youtu.be/Dpa7oTXaRnw

Did you check and see if the air pump is strong enoug to blow air through the viscous material that will be in your tank. I put a Sweetank in a previous boat that had a horrible problem when you flushed a head. Fixed the problem in 2 hours of air flow into the tank. Let us know how yours works out. We ran the Sweetank 24X7 and never put any chemicals in the tank again and absolutely no smell.

Comodave said:

Did you check and see if the air pump is strong enoug to blow air through the viscous material that will be in your tank. I put a Sweetank in a previous boat that had a horrible problem when you flushed a head. Fixed the problem in 2 hours of air flow into the tank. Let us know how yours works out. We ran the Sweetank 24X7 and never put any chemicals in the tank again and absolutely no smell.

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Good question. I don’t know if it will get through the sludge. However, I think it will. No way to know until I get it in the tank.

It would be crappy if it doesn’t...

I installed the Profile tank monitor last weekend. All went well and it at least registers empty and full. Not sure of the intermediate at this point. One issue is that I have a SS fitting for a hose that enters the tank between the foil sensor strips. There just wasn't any place to install them. We'll see how that affects the accuracy. One other issue which I knew about is that the cut-out for the old TankWatch display is larger than for the Profile display. So I'm going to need to make up a backing plate to mount the Profile display. Hopefully in a way that won't offend the aesthetic sensibilities of my wife.

It has to be calibrated (see the installation instructions) to give you all the levels accurately. Best to do that with just water in the tank. Give Dennis a call if it's not calibrating as it should.

Replacing the SS fitting with a plastic one would eliminate any problems with it. And if you mount the display panel on a nice framed piece of varnished wood or maybe some Corian or other countertop stuff, she'll be ok with it, especially if you let her pick it out.


--Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein

HeadMistress said:

It has to be calibrated (see the installation instructions) to give you all the levels accurately. Best to do that with just water in the tank. Give Dennis a call if it's not calibrating as it should.

Replacing the SS fitting with a plastic one would eliminate any problems with it. And if you mount the display panel on a nice framed piece of varnished wood or maybe some Corian or other countertop stuff, she'll be ok with it, especially if you let her pick it out.

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I calibrated it at the empty and full point per the instructions as well as set the tank shape. The tank was empty when I installed it so I set the Empty point, then filled the tank with water and set the Full point. So we’ll watch it as the tank gets filled from use and get a sense of how the 1/4, 1/2, and 3/4 levels read.

Good idea to swap out the SS fitting with plastic. Not an easy job, but I might do it if it seems to be skewing the readings too much.

I don't know how much it actually matters, but from the installation instructions for the SCAD SOLO-1: "If possible, avoid calibrating holding tanks with fresh water since wastewater is not sensed exactly like fresh water."

porman said:

I don't know how much it actually matters, but from the installation instructions for the SCAD SOLO-1: "If possible, avoid calibrating holding tanks with fresh water since wastewater is not sensed exactly like fresh water."

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I'm not sure either. The nice thing about the monitor is that the Full or Empty point can be re-calibrated at any time. My tank wasn't completely empty when I calibrated the Empty position. I had pumped it out myself and when I do it I leave the tank emptier than when the local Pumpout Guy does it. Even so, there is definitely fluid in the bottom of the tank. However, that is as empty as the tank is very going to be.


Filling with fresh water doesn't mimic a full holding tank exactly, but it is a good place to start. I can re-calibrate the Full again when I have the tank as full as I want it to be. To be honest, I filled up the tank more than I would have liked with fresh water so I'll want to re-calibrate again anyway.

dhays said:

Good idea to swap out the SS fitting with plastic. Not an easy job, but I might do it if it seems to be skewing the readings too much.

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The readings are generated basically by the capacitance between the two strips of foil on the outside of the tank. Unless the metal fitting is very near or in between the two strips it should not affect the reading.


I believe Peggie's suggestion to get that metal fitting out of there is more based on the fact that few metals survive very well in that environment.


Ken

dhays said:

I'm not sure either. The nice thing about the monitor is that the Full or Empty point can be re-calibrated at any time. My tank wasn't completely empty when I calibrated the Empty position. I had pumped it out myself and when I do it I leave the tank emptier than when the local Pumpout Guy does it. Even so, there is definitely fluid in the bottom of the tank. However, that is as empty as the tank is very going to be.


Filling with fresh water doesn't mimic a full holding tank exactly, but it is a good place to start. I can re-calibrate the Full again when I have the tank as full as I want it to be. To be honest, I filled up the tank more than I would have liked with fresh water so I'll want to re-calibrate again anyway.

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I set up and calibrated mine the same way as you did and its worked out just fine, but like you said, you can adjust it at any time. 4 years on and its still perfect. Definitely one of the better updates I added.


Ken

kchace said:

The readings are generated basically by the capacitance between the two strips of foil on the outside of the tank. Unless the metal fitting is very near or in between the two strips it should not affect the reading.

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That is the potential problem. It is exactly between the two strips. the other option would have been to place the strips with the fitting right next to one of the strips. Not ideal but my thought was that while it may affect the intermediate readings somewhat, it will at least be consistent.

First time I've heard that...sounds like I need to give Dennis a call!


--Peggie

dhays said:

That is the potential problem. It is exactly between the two strips. the other option would have been to place the strips with the fitting right next to one of the strips. Not ideal but my thought was that while it may affect the intermediate readings somewhat, it will at least be consistent.

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Yeah it's probably fine because the system was calibrated with it.

Ken