Holding tank sediment

[Capecodder]

When I purchased my trawler I was told I had 45 +/- holding tank. As I traveled and pumped out it was always a Mystery of the volume extracted. Once in Baltimore harbor tank was full as indicated by Tankwatcher alert light. Mobile pump out only extracted 25 gallons?
Scheduled pump outs the last year or so always under 20gallons, with warning light on a few times it was about 25 gallons.

Recently had some “Drain Flys” and internet suggested enzyme treatment for pipe cleaning. I purchased a bottle of Zep Drain Care at HD for cleaning shower drain. Had lots left over and used some in the head. Was surprised at next pump out extracted close to 40 gallons..... stopped as portable tank was full.
I have consistently used one of the highly recommended holding tank treatments and had no odor issues, but never extracted more than 25 gals. Today at the next scheduled at pump out with normal use expecting 20 gallons he pumped 35 + gallons and had to stop his tank was full.

So my long story as typed on a phone, the Zep seems to have digested a layer of sludge and increased useable storage.
.
Btw no changes in uses or pump out Cart equipment .

 

[HeadMistress]

Although there's sure to be some sludge accumulation on the bottom of your tank if you've never flushed it out (that should be done a few times a year...not difficult to do), it's unlikely to be deep enough to reduce your tank capacity. If it were the tank discharge would be completely blocked, making it impossible to pump the tank out. If your tank level indicator is one that has senders inside the tank the problem is most likely a buildup of the animal fats in waste on the senders that are clogging 'em.

The cure: pull the sender unit and put it in a bucket of water with about a quart of liquid detergent in it. Let it soak overnight, then hose it off (you may also have to use a brush to get it totally clean). You'll prob'ly have to do this about every 2 years.

Or, you can replace the system with one that has senders which attach to the outside of the tank and never have to clean 'em again. The Profile system Profile Tank Monitors is the best, top rated by Practical Sailor.

To flush the sludge out of your tank, put enough water into it via the deck pumpout fitting to cover the bottom to a depth of about 6"--'cuz that sends the water into the tank at the bottom to stir up the sludge and hold it in suspension so it can be pumped out. Pump that out...repeat...repeat...till you're pumping out clean water.

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

 

[HeadMistress]

I just pulled up the MSDS for Zep Commercial Drain Opener. The active ingredients are:

SODIUM HYPOCHLORITE; hypochlorous acid, sodium salt; bleach 7681-52-9 1 - 10
SODIUM HYDROXIDE; caustic soda; soda lye 1310-73-2 0 - 5
POTASSIUM HYDROXIDE; caustic potash; lye

None of those ingredients are recommended for use in a marine sanitation system because they're caustic and damaging to hoses.

"Reactive or incompatible with the following materials: organic
materials, metals and acids. Incompatible with ammonia."

Toilet waste consists of organic materials and ammonia (urine).

So I'm guessing that along with anything else it might have done, it cleaned the tank level senders enough to give you accurate readings again and dissolved any sea water mineral buildup in the discharge line. Better to just maintain the tank and vent line to make sure it never becomes blocked and stick with products recommended for use in marine plumbing.

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

 

[Xsbank]

"Noflex Digester" works very well if you have adequate tank vents. It ate all the sludge out of my 20 year old tank before I threw it away. Hypochlorite kills ALL bacteria and eats the chrome off your fittings. Wrong solution (in both senses).

My new tank has 2 - 1.5" vents, one at the flare of the bow and one midships, we get great flow through the tank now.

 

[Codger2]

Although there's sure to be some sludge accumulation on the bottom of your tank if you've never flushed it out (that should be done a few times a year.......

If your tank level indicator is one that has senders inside the tank the problem is most likely a buildup of the animal fats in waste on the senders that are clogging 'em.

Or, you can replace the system with one that has senders which attach to the outside of the tank and never have to clean 'em again. The Profile system Profile Tank Monitors is the best,

Great advice as I followed her advice years ago & haven't had a problem since!

 

[tiltrider1]

After living on my last boat for 10 years I had to pull the holding take to replace a broken fitting. I never used any chemicals in that tank. I opened the top of the tank expecting to find all kinds of sludge. There was no sludge. I think sludge build up is highly unlikely.

 

[Capecodder]

I just pulled up the MSDS for Zep Commercial Drain Opener. The active ingredients are:

SODIUM HYPOCHLORITE; hypochlorous acid, sodium salt; bleach 7681-52-9 1 - 10
SODIUM HYDROXIDE; caustic soda; soda lye 1310-73-2 0 - 5
POTASSIUM HYDROXIDE; caustic potash; lye

Hi,

Thank you for the quick response! I have purchased your book twice and have read it cover to cover. I loaned out the paper back.... then had to download the update version...

I am not a A chemist but, I think we are talking about different products. I may of attached a photo for the product I was talking about. I wouldn’t intentionally use a lye product in any drain. I did once 20 yrs ago and learned my lesson.

https://images.homedepot-static.com/catalog/pdfImages/8d/8d73034f-f1d9-4af0-8788-486dce5f6755.pdf

 

[Chrisjs]

I believe the Tankwatch is adjustable for different fluid levels. Suggest you take top off tank (after pump-out an flush!!) and take a look. Perhaps your Tankwatch needs adjusting to detect correct levels

 

[HeadMistress]

You'll find a diagram showing the senders in a TankWatch and instructions for installing and using it here:
SeaLand TankWatch 3 Level Monitoring System User Manual | 2 pages

And I'd bet real money that the senders need to be cleaned if the TankWatch has been in the tank 2-3 years. They're known for getting clogged by the animal fats in waste. The same wiring will work with the Profile gauges, so it's only necessary to replace the senders.

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

 

[Capecodder]

I’ll assume that I’was not clear in my original post.

The tankwatch alert system, with its limitations was and is not the subject of my post. The light signals when tank is full, and that usually only happens when I’m flushing the tank with a hose.

I used a product that seems to have drastically increased the available/useable holding tank volume. No changes to the normal uses or equipment.

On a Sunday morning, I’m spending time posting about a poop tank, time to watch the talking heads for the “news”

Thank you everyone for the great assistance provided on this forum.

The never used intentionally Used Lye in the system...