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Old 02-05-2020, 04:30 PM   #1
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2016 27' International
San Anselmo , California
Join Date: Nov 2014
Posts: 63
Geo Method 2.0

Geo Method 2.0
If you love hours of online entertainment, studying methods of keeping your holding tanks clean, then add this updated and less expensive system to your knowledge base.
When we went fulltime five years ago, it didn’t take us long to discover that keeping our black and grey tanks clean was essential, and we were very “green” in our understanding. We were told that single ply toilet tissue would be necessary, but quickly found that these types of rolls were often costly, hard to find, contained a meager amount of paper, and required much more of it to do the “job.” Early on, after working through clogged trailer dump ports, we found that before dumping black tanks, they should be near 80 to 90% full to increase water pressure, hence a more complete “flush.” Then we began to notice tank readings became erratic due to tank surface build up. This all lead to the discovery of the Geo Method, thanks to Charles Bruni, in the 1980s.
We also took a major step toward solving our problem by eliminating toilet paper in our tank. We purchased a stainless steel vegetable recycling can with carbon filters from Bed Bath and Beyond, put in liners and all paper was easily and sanitarily disposed in trash. This went a long way toward solving our concerns. The next step would be to solve the tank build up from human waste, leading to the discovery of the Geo Method, and it worked!
If you haven’t read about this technique, google search it, but a simple recap is the use of surfactants in the tank water to reduce surface tension, allowing the “dark matter” to easily move through into the sewer. Geo Method 1 calls for the mixing of 2 cups of water softener, Calgon is mostly used, with one cup of laundry detergent in residual tank water, after every dump, and an occasional use of bleach as a disinfectant.
We soon found though, that locating Calgon was problematic, and if found, was pricey. Each bottle at Walmart costs approximately $5.50 and will provide only two applications. Inexpensive laundry detergent, “Roma” for example, runs about $8.50 for a 176-oz bag. (It does come in larger bags but space is always a concern.) We found ourselves spending about $105 for 35 dumps (~$3/dump), not too sustainable in our lifestyle.
Geo 2.0
We wondered what chemical source would provide sufficient “lubricity” to our tank water to replace Calgon and a light came on. Our use of Dawn Ultra would make oils and fats melt away in our dishwashing. This effectiveness could easily replace the Calgon at an outstanding improvement in cost. A 75 fl oz bottle of Dawn costs around $9.00 and provides around 35 3-oz applications. Again the 176-oz Roma or equivalent detergent runs at approximately $8.50 for the equivalent one-half to one-cup use. The cost estimate factor for this method comes to about $17–$20, or 57˘ per application vs. $3.00 in Geo 1, a significant savings.
The upshot of the Geo 2 scheme is that our black tank runs clear after several successive dumps and we can observe surfactant soap bubbles streaming through our dump hose even after several dumps in one session, evidence of efficacy. Also as a result, our tank SeeLevel 2 readings are consistent and accurate throughout the reading range.
Incidentally, we just installed a bidet seat in our 2016 Serenity, and this has radically reduced most toilet paper use, taking our efficiency to another level, but that is another story…
The Geo 2.0 method may not be the be-all end-all of black tank cleaning, but it can be an asset in your tank management arsenal.

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Old 02-05-2020, 05:00 PM   #2
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2016 25' Flying Cloud
Jupiter , Florida
Join Date: Nov 2015
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We've been priming the black tank using a little Calgon (capful), Happy Camper (scoopful) and Dawn (big squirt), each in their own bowl full of water for years now, and we've had no problems. We also avoid putting paper down the toilet.

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Old 02-05-2020, 05:11 PM   #3
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Fair Oaks Ranch , Texas
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What size black tank do you have? We use a capful of Calgon and a detergent pod after each dump of our 18 gallon black tank. A bottle of Calgon lasts quite a while. We run clear with a second fill and dump. No issues after four years. I can see where Dawn would work well too. I add Happy Camper when in storage. Mike
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Old 02-06-2020, 12:02 AM   #4
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2016 27' International
San Anselmo , California
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39 gallons, brother.
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Old 02-06-2020, 12:31 PM   #5

2003 25' Classic
Zanadude Nebula , Milky Way
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Used the Geo 9 years ago when the level sensors stopped working.
Now it's just, drive 50-100mi before dumping, flush well, 3oz of dawn, HappyCamper.👍

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