Aeration pumps for holding tanks

[colemj]

Originally Posted by doublewide

I should sell these things. Buy yourself a 12V bait tank aerator and run the aerator hose to a hose barb you fabricate in the top of your holding tank. Just buy a barb and drill and tap into the most suitable part of the tank top. That blows fresh air into the tank continuously. This is enough to stop the growth of anaerobic bacteria. Anaerobes are the stinky kind of bacteria.

Next fabricate a vent scrubber out of about 18 inches of PVC plumbing pipe with appropriate end caps and hose barbs, and if you want to be able to change the filtration material every year or so, make one end removable; fill it with activated charcoal granules from the pet store aquarium section, and slap your new scrubber into the tank vent line. Result: No holding tank odor, ever. And the parts are cheap.

If what is described in your first paragraph works, then it negates the need for what is described in your second paragraph.

Mark

[Cap Erict3]

Look at Red Fox sewerage treatment systems. They have been around a long time.

You won't buy one but u might get some ideas.


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Looking for another pretty place to work on the boat.

[knight raven]

I have followed with interest this conversation and note , Peg:-
It's actually very rare that tanks smaller than about 40 gallons need aeration to eliminate odor...UNLESS the tank is buried in a deep bilge and has a overlong convoluted vent line. In 90% of tanks passive ventilation above the surface is all that's needed.
I have a small 30 litre holding tank newly installed. Capt Rob Cozens notes that ventilation hoses don't help when angled above 45 degrees. Mine is well above that. He notes that a cross flow of air does suffice to eliminate the odour of anaerobic bacteria. Installing another vent is not my option.
Simply, pumping air into the tank should aid the odour elimination. However I am awaiting the outcome of using fresh water rinsing after pumping dry, and ensuring a dumping inside legal limits before marina docking.
If that is insufficient, I shall look to installing a wee aerator (no pun intended) powered by 12V.

[peghall]

If you stumbled across Rob Cozins' article "Marine Toilets: What You Should Know," the information in it is good--at least as far as it goes---although much of it is hopelessly out of date...and I should know...'cuz he didn't write it, I did. It was my first published work, titled "Marine Sanitation: Fact vs. Folklore" copyrighted and published in 1994 and updated for the last time in 1997. Cozins simply changed the title and put the whole thing on his website over his own name and even had the gall to claim "copyright 1998, Captain Rob Cozen, all rights reserved." I've asked him to remove it several times, but he ignores me. Almost everything in it that isn't subject to laws of physics (those never change) has become so hopelessly obsolete that it's not worth going after someone in court who prob'ly uncollectable anyway. If you do a search for it under its original name you'll find all kinds of references to it--and me as its author.

And now that I've got THAT off my chest...

"Capt Cozins" notes that ventilation hoses don't help when angled above 45 degrees.

That's true as a "rule of thumb," but not cast in stone....I've learned quite a bit in the 20 years since I wrote that piece! Depending on where the vent thru-hull is located on the boat and the type of thru-hull, diameter of the vent line and other factors including the tank product, it is possible for a vent line that rises more than 45 degrees to provide sufficient oxygen to suppress odor generation.

He notes that a cross flow of air does suffice to eliminate the odour of anaerobic bacteria. Installing another vent is not my option.

True, but also rarely necessary for a tank that small. A couple of minor mods should be enough.

Simply, pumping air into the tank should aid the odour elimination.

Again..maybe...maybe not.

We need to talk...send me an email?

[knight raven]

Hi Peg
Well well well, we do live and learn.
In any event my thanks for your response. I am on a steep learning curve here.
Wishing to replace a tiny 10 litre holding tank.......gravity used to empty, I engaged a company to install a 30 litre one. This, under the settee. Not a best job as the 'plumber' left a sag in the main hose being presumably too lazy to shorten his "near-enough" over long ones. I shortened it.
So the original vent which was about 10" vertically out of the small tank, has been replaced by one exhausting in the same place, but now descending further down, to the top of the new tank sited at floor level beside the centre walk way. So it would be about 5 feet in length running across the new tank, through the outer cubby hole thru' the bulkhead and straight up behind the head and exiting just below the toe rail.
I think I have solved the sulphur dioxide (?) smell by paying attention to flushing properly after use and at the day's end putting fresh water through the head (with a Milton tablet) and after dry pumping that, leaving a kettle full of fresh water in the bowl until next time out on the briny.
The idea is that if that don't work I consider passing air into the top of the holding tank with, say an acquarium aerator. I would be assuming that the small tank religiously dumped at sea each day, then thusly treated at the Marina, should be enough.
But it does no harm to think ahead.
I enjoyed your earlier comments in the forum.
I'm glad you're upright and breathing, and available for a stimulating read.
My best
Neil Hilford
NZ

[peghall]

You've managed to apply several "band aids" to your system, but you really need to fix it properly. I can be available for a Skype discussion if you'd like my help to determine the easiest way to do that.

[knight raven]

Thanks for that but tis really early days, given that the system is new.
New tank, new hoses.
I certainly hope the expenditure hasn't been a waste of my money, given the wish to have something bigger (than a ten litre). I don't think I would want to go back to that simple but too-small an option.
I'll come back after some more time on the briny.
Cheers

[peghall]

It's not the equipment that's the problem, it's how it's installed. That's easy to correct.

[knight raven]

i have no reason to suspect the current installation. Hoses pretty straight with no sags now.

[Simi 60]

Just stumbled into this thread trying to find out what the disconnected air pump on my system did when it was plugged in for the original system.

We have 2 fresh water flush toilets
Previously it had an aquasan sbsII system (old panel still there) but now has
2 saniloo treatment plants
All going into a 152 us gallon or 576 litre holding tank which we pump over the side on passage every month or so.

Plugged in the 240v Hi blow hp40 pump today and heard it blowing bubbles so I am thinking it'd be worth turning it on and stirring the pot so to speak 5 minutes before pump out as it seems to be rather a thick brew towards the end of the pump out so far.

Comments?

[peghall]

I don't think you quite grasp what an aerator does. It oxygenates the tank, which prevents the waste from generating smelly gasses. It needs to run 24/7/365 (except during winter or other extended layup) to do that. It will not stir up the sludge in the bottom your tank...that requires you to actually flush out the tank 2-3x season whether there's an aerator in it or not. It's not hard to do and you don't have to fill up the tank to do it.

Put enough water into the tank via the deck pumpout fitting--'cuz that sends the water into the tank at the bottom to stir up any sludge and hold in in suspension so it can be pumped out--to cover it to a depth of 5-6". If you have a washdown pump (can be sea water) and macerator pump, let the water continue running and turn on the macerator. Let them both run till you're discharging only clean water.

Now turn on the aerator and let it run continuously. If it's doing its job you should have no odor out the vent when you flush.

If you don't have the owners manuals for your toilets, Saniloo and the aerator, I strongly suggest you get them...you should be able to download them from the mfrs' websites. If you already have them, read them to learn how to operate and maintain everything.

Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein
http://www.amazon.com/New-Get-Rid-Bo...dp/1892399784/
(also available from Boat Books Australia)

[Simi 60]

Thanks Peg.
We have the saniloo manuals and know all about them and the holding tank gets "treated" sewage from them.

We have been living aboard at anchor for near on a year now, have never ran the air pump until today and have had no weird smells in the past so not convinced that we'd need to run it 24/7 if at all, especially seeing as its a 240v item.

We have no deck pump out as pump out facilities in oz are almost non existent.
We do have a ball valve in the bottom of the tank so I have doctored up a barb/hose/PVC pipe arrangement to attach a deck wash hose at a higher than top of tank height .

I will give it a run doing a flush as suggested.

Thanks.

[valhalla360]

The problem with a bellows is most people anchor/dock where there isn't a lot of wave action, so the bellows likely won't do much. If there is a lot of wave action, the movement of the water will create natural airflow and water circulation negating the need to aerate.

I wouldn't waste money on a "marine" aerator. Just pick up any basic aquarium air pump. Literally under $10 with some plastic tubing and something to weight the end of the tube down (wouldn't use an airstone as they plug up eventually and I wouldn't want to be fishing it out to replace regularly).

Any of these pumps can get air to the bottom of the tank which will create water circulation and add oxygen to the water far better than any surface airflow. I just looked and most are in the 5-10w range so if you have shore power or a decent solar system, it can run 24-7 with power consumption being largely a non-issue. They are designed to run 24-7 in a humid environment so no issues with using them on a boat. If they fail in a couple years, it's only $10 to get a replacement, though I've had them last a decade or more in aquarium use.