Replacing the Holding Tank Starting Tomorrow-Wish Me luck!

Larry M wrote:My mistake.* I didn't realise the outlet for your macerator is at the top of the tank.*


Larry/Lena
Hobo KK42
La Cruz, Nayarit, MX*

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Ok thanks Larry I thought I was missing something!* We decided to go with the outlets on top at Peggy's suggestion.* We hope they do allow for more complete emptying as advertised--it makes sense that they would.* With the old nine gallon tank there was always at least as gallon left in it.*

*

No valve, no problem. Just go to your nearby pumpout and empty and flush the tank. And in Alaska or the South Seas, the nearest pumpout is only - a day or five *trip away?? Oh Oh.

sunchaser wrote:

No valve, no problem. Just go to your nearby pumpout and empty and flush the tank. And in Alaska or the South Seas, the nearest pumpout is only - a day or five *trip away?? Oh Oh.

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LOL luckily we are in the SF bay and there are pumpouts everywhere!* Not planning on going far afield in this boat.

The hassle with a top outlet is the macerator or pump out pump must be in perfect operating condition as it must be able to create a vacume.

Almost all the diaphram pumps will fail at this as the pump is usually not flushed after each discharge , so the tinyest piece of paper may keep the intake flapper from the perfect seal.

IT can be done to create an easy flush system for clearing the discharge system , but it required a bit of extra plumbing and procedures..

A different simple solution would be to overfill the waste tank an hour before pumping , which would wet the discharge pump and remove the lift requirement.

The RV industry has excellent valves that can be installed in the bottom of the tank, so removing (twist off) to repair a pump would be somewhat easier.

The 120V macerators are far better than the 12V , even with #8 wiring.

The Galley Maid (about $1200) has a flush water inlet , but the initial price is hard to justify , untill you clear rebuild a dozen cheap units underway

I don't understand why all tanks (fuel,water,waste) don't have the outlet in a sump at the lowest possible level. The crud can never happen if your pumping from the bottom, every other solution only creates problems that don't need to exist in the first place. When I pump out the holding I want to pump out the holding. I don't want a single ounce of "stuff" in there. When I filter the fuel I don't want to filter only what's above the bottom 10 gallons. If the fuel isn't sitting at the bottom then you'll never have crud in the first place.

Hiya,
** Mr daddyo.* I think Mr. FF has covered that question several times.* The reason for no bottom drain is the builder wanted to save a few bucks and didn't care about future maintenence problems/issues for the owner.

Daddyo wrote:

I don't understand why all tanks (fuel,water,waste) don't have the outlet in a sump at the lowest possible level. The crud can never happen if your pumping from the bottom, every other solution only creates problems that don't need to exist in the first place. When I pump out the holding I want to pump out the holding. I don't want a single ounce of "stuff" in there. When I filter the fuel I don't want to filter only what's above the bottom 10 gallons. If the fuel isn't sitting at the bottom then you'll never have crud in the first place.

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I agree with the holding tank and maybe even the water but not with the fuel.* Cars and trucks are like boats and the reason is that the dirt or water will*foul the filters right away and strand you out in BFE.* Now I know that folks get stranded on both land and sea but if they really did there maintenance as needed that wouldn't happen except in the rare occasion.**But if you think about how much stuff has to be in there to*foul the filter it gives you an idea as to how long folks let the regular maintenance go with out any attention given to the tanks at all.

*

I've got to disagree. remember we're talking about tanks that are drawing from the very bottom in the first place, because of this there isn't going to be any stuff. The stuff only occurs because we have fuel coagulating on the bottom of the tanks. If you are drawing from the top down with a standard tank then you've got stuff at the bottom of the tank that becomes "in suspension" in a trying sea state. If you've ever been in these conditions and have a vacuum gauge on your filter/s then you can see what mixing up this stuff does. It is a recipe for engine shut down unless you have multiple filters and or fuel polishing. With the true bottom pick up there are no rough sea surprises.

My complaint is not the need for a simple bottom drain plug.

This will help , but not cure the fuel/ water interface where the problems start.

I want to see a SUMP, think of a coffee can built into the bottom of the tank that can be pumped , or drained as part of the PM or pre sail.

Daddyo wrote:

I've got to disagree. remember we're talking about tanks that are drawing from the very bottom in the first place, because of this there isn't going to be any stuff. The stuff only occurs because we have fuel coagulating on the bottom of the tanks. If you are drawing from the top down with a standard tank then you've got stuff at the bottom of the tank that becomes "in suspension" in a trying sea state. If you've ever been in these conditions and have a vacuum gauge on your filter/s then you can see what mixing up this stuff does. It is a recipe for engine shut down unless you have multiple filters and or fuel polishing. With the true bottom pick up there are no rough sea surprises.

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At the risk of being like some others here.**In a fuel tank*you are not drawing from the top down.* You are*drawing from the bottom, all be it an inch or so from the bottom it is the bottom, just not the very bottom.* The "stuff" you refer to is also on the sides of your tank as well as the bottom.* It is the dead bodies of the Algae that thrive in warm Diesel fuel.* So heavy sea action will set it free from the sides as well as the bottom.

So I don't agree that with a true bottom pick up that you will not have a problem in heavy seas.* Even FF's sump (which I like for water and sediment collection)*will still have the Algae build up if the fuel is not treated properly or is not*a high consumption boat with a lot of turn over.* A day tank system for instance will not have the problem of the residue collecting because of the high turn over rate.

And yes I think there is nothing like the two filter system with the capability of switching while under way.

Just my opinion.

-- Edited by JD on Thursday 25th of November 2010 08:11:50 AM

HI Jen...congratulations on a job well done! As always around here, you got a lot of advice and opinions, some of which was even GOOD advice!

Hope y'all are having a good T'giving!

Peggie (out of town TFN)

"Algae build up"

What makes you think its ALGAE? That lives at the fuel/water interface in your tank?

"The hassle with a top outlet is the macerator or pump out pump must be in perfect operating condition as it must be able to create a vacume."

!
Fred.......that's sheer nonsense. EVERY tank pumps out from the bottom. So if the discharge fitting is at the bottom of the tank, the entire length of the discharge hose from the discharge fitting to the deck pumpout fitting is outside the the tank. If the fitting is on the top of the tank, there's a pickup tube inside the tank that connects to a hose that goes the rest of the way to the deck pumpout fitting. So when it comes to the macerator or pumpout, IT DOESN'T MATTER WHETHER THE PUMPOUT LINE IS INSIDE OR OUTSIDE THE TANK!!

And as for drains ON the bottoms of tanks...that won't work unless the entire tank is above the waterline.*

Ya gotta love Fred and RT...cuz without 'em this place would be SO dull!


-- Edited by HeadMistress on Friday 26th of November 2010 08:48:44 PM

Hiya,
** Aw c'mon HM, I'm not even on the same page as FF.* Cut me some slack here would ya.

For a somewhat different perspective on the topic of "algae" in diesel fuel, here is part of a post I came across on a forum for long-haul truckers. The topic of the discussion was not unlike what we have on boating forums--- the issue of algae forming in the water/fuel interface in fuel tanks. According to the writer--- and numerous other ones on similar forums I've looked at--- the notion of "algae" growing in the water that can get into a fuel tank via leakage or condensation and feeding off the fuel is not what is actually happening.

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"Saying that what is referred to as "algae" is created by condensation is totally incorrect. Diesel fuel that is left to stagnate in tanks (in as little as 60-90 days) breaks down much like gasoline does and creates the "algae" or silty crud at the bottoms of tanks. The black, gooey, stringy stuff that occurs after sitting for long periods of time is actually the results of the fuel breaking down. That slime is actually paraffin wax and asphaltenes. It is more prevalent in today's fuel as a result of the refining process. There is actually no live algae growing, as Winslow said, although bacteria and microbes do help accelerate the breakdown process.
The algacides actually break up this mess and break it down so it can be filtered out.

Condensation in any tanks creates a big problem because the water cannot be atomized and burned in a diesel engine. Boaters keep their fuel tanks full to avoid the condensation water which does major harm to the injectors and internal engine components such as heads, pistons, bearings, etc., and unlike vehicles, there's nowhere to pull over when your out to sea and the engines quit."

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Hiya,
** Algae is a plant and needs sunlight to grow.* The "growth" in fuel tanks*is bacteria which lives in the water and feeds off the oil.* As with any living organism, the bacteria eventually die and if enough are present in the tank, can form a large biomass which will clog filters.* That, coupled with what Mr. Marin just posted, is just one more thing to watch out for.

RT*- Even HM has you pegged.

Pegged????**

Marin wrote:Condensation in any tanks creates a big problem because the water cannot be atomized and burned in a diesel engine. Boaters keep their fuel tanks full to avoid the condensation water which does major harm to the injectors and internal engine components such as heads, pistons, bearings, etc., and unlike vehicles, there's nowhere to pull over when your out to sea and the engines quit."

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RTF is absolutely correct about it not being algae. There are plenty of posts on this site about that issue ... several of them by me so they must be true.

Condensation provides the water that bacteria (not algae - algae is a plant that requires light to live) need to thrive. Fuel does break down and produce asphaltenes which accumulate on the tank bottom and on the mat of bacterial colonies.

Water will atomize nicely and actually helps reduce some of the environmental negatives of diesel combustion. Unfortunately, diesel fuel systems are not designed to handle contaminated water and the injectors will corrode and sieze very rapidly when water is admitted to the system.

You have the entire ocean in which to "pull over" at sea.* Would much rather have an engine failure at sea than in a truck on the I-5.*



*

"If the fitting is on the top of the tank, there's a pickup tube inside the tank that connects to a hose that goes the rest of the way to the deck pumpout fitting. So when it comes to the macerator or pumpout, IT DOESN'T MATTER WHETHER THE PUMPOUT LINE IS INSIDE OR OUTSIDE THE TANK!!"

I'll use smaller words.

There is seldom a problem wit pumpouts that are done DOCKSIDE with commercial equipment.

These are frequently Obendorfer 120V pumps and are flushed after most uses.

The hassle comes from the cruiser that wishes to use an on board pump to discharge "offshore".

Here either the pump must be located down low , so it stays wet inside , as mounting a typical boat or RV maceriator or diaphram pump is fraught with risk.

IF it is above the tank, at least its easy to get to to service, but the diaphram units do poorly at inital lifting , and most macerators are limited to 4 ft vertically for suction.

Just as boat stuff comes in multiple quality levels RV equipment is similar.

For the critical shut off valve at the bottom of a tank , the Dupree valve setup would be my first choice,.

For the pumpout pump either the Obendorfer or Galley Maid , will frequently run decades .

IF 12V Yachty stuff is chosen , at least feed it with #6 or #8 wire and a 20-30A circuitbreaker.





-- Edited by FF on Monday 29th of November 2010 06:01:05 AM

Two comments, one on each recent point, both from experience, one bitter, one good.
FF is right in that most macerator pumps which allegedly will self-prime to at least a metre, in fact don't - not if left for any time in my experience anyway. My TMC was suposed to do so, and is only mounted about a foot above the outlet from my holding tank, but unless used very recently I have to prime it by routing some water back down the outlet to the pump first, before it will pump out.
The second point is to support Daddyo re the virtues of bottom take-off of fuel lines from tank. Yes, the constant shaking up and the fact any dirt or water is sucked out constantly means it just does not accumulate. How do I know? Well, I often commit the sin of only having my tanks half full, (or less, as diesel is dear here ($Aus 1.50 a litre = $US6 per US gal), and even so, I rarely drain more than a teaspoonful of water from the separator in the primary filter, and I have only changed the actual filters once in 7 yrs, because each time I check them they look too clean, and I'm very much an "if it ain't broke don't fix it kinda guy. The engine has never missed a beat in all that time. Do we have cleaner diesel here in Oz than you in the US - I think not...?

Peter B wrote:FF is right in that most macerator pumps which allegedly will self-prime to at least a metre, in fact don't - not if left for any time in my experience anyway. My TMC was suposed to do so, and is only mounted about a foot above the outlet from my holding tank, but unless used very recently I have to prime it by routing some water back down the outlet to the pump first, before it will pump out.

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Most likely that's not because the pump can't prime, but because the impeller must be freed up first.*

Waste is sticky...so when a macerator pump is left to sit for any extended time without first rinsing it out, the impeller sticks to the housing...sometimes stuck tightly enough to break a vane before it lets go.*

Trying routing some clean fresh water down the outlet through the pump immediately after using it and I THINK you'll find that it will have no trouble priming the next time you use it.* I would definitely rinse out the tank and pump very thoroughly in preparation for winter layup.

*

I have the same problem. Even with new impellers mine often requires priming. It is such a common problem I am considering adding a T in the discharge line so I can prime easily.

HeadMistress wrote:
Trying routing some clean fresh water down the outlet through the pump immediately after using it and I THINK you'll find that it will have no trouble priming the next time you use it.

*

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When we installed a new aft holding tank I modified the plumbing to include a short stand-pipe with a removable cap that I pour a gallon or so of fresh water into and run it though the standard Jabsco macerator pump after every cruise on which we use the pump.* I have no idea if this is helping but we've had the boat for over twelve years now--- we installed a new pump right after buying the boat and I just had to install a replacement a month or so ago.

*

HeadMistress wrote:Most likely that's not because the pump can't prime, but because the impeller must be freed up first.*

Waste is sticky...so when a macerator pump is left to sit for any extended time without first rinsing it out, the impeller sticks to the housing...sometimes stuck tightly enough to break a vane before it lets go.*

Trying routing some clean fresh water down the outlet through the pump immediately after using it and I THINK you'll find that it will have no trouble priming the next time you use it.* I would definitely rinse out the tank and pump very thoroughly in preparation for winter layup.

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Thanks for the suggestion Peggy, but I do let clean water siphon back thru the pump after the pump-out, being below the water line, and not having (needing) a bleed/anti-syphon valve I can do this, and the pump is definitely spinning, not jammed when it fails to self-prime.
I have set things up so I can send open and close valves to allow a quick flush back down the outlet line to the pump and that fixes it - it's just annoying to have to mess about doing it, that's all.* Oh, and of course important to re-set all the valves back the right way after doing it of course.* Oh, and by the way - not to rub it in, but we don't have an 'off' season here.* We boat all year round - like in Florida.

*


-- Edited by Peter B on Sunday 5th of December 2010 05:35:30 AM

How old is the pump? When, if ever, was the impeller replaced last?* The edges of the vanes do wear over time, from dry friction till the pump primes. It's such even wear, with no sign of heat that a visual inspection won't reveal it...but as the edges wear just microscopically the pump becomes less and less efficient, 'causing the pump to take longer and longer to prime, wearing the impellers more... till finally it the impeller can no longer pull (impel) anything through it.* Letting the pump run even for a short time after the tank is empty accelerates the wear.

So impellers really should be replaced as preventive maintenance at least every 2-3 years...annually if the pump is used a lot.* Which is one more good reason to spend the extra money for a diaphragm pump...'cuz it only takes a few impellers to run the cost of an impeller pump up to more than the price of a diaphragm pump.

And while YOU may be able to use your boat all year long, not everyone reading this discussion can.* Years ago I read it was estimated* that for every forum discussion participant, there were at least 10,000 anonymous lurkers who never register or ever say a single word.* While I can't vouch for the validity of that number, I 'd bet real money that there's at least one person reading this who does lay his or her boat up each winter. I try to write for them too.

HEH HEH, Not called Headmistress for nothing

Well now that I have the engine out of the boat I am going down the path of replacing my sewage system.
Took delivery of my Electro Scan today (7 day delivery feom Defender in USA)
I am off to see the the Atlas tank people tomorrow to make a new holding tank.
probably about 140 lts (35 gal)
This can all go in whilst I have some space .
The system I had in was an Auto San system made here in Qld and has never been a complete success. Very smelly mostly to do with the lack of air flow but I did have 2 x 1" vents on the tank. This system was a metered chlorine injection type.
Have removed the old holding tank (very stinky business) and cleaned up the corner.
Good clean work from here on in.

Peggy with the discharge from the Electro Scan going to a holding tank will it require cross flow ventilation or will the discharge liquid be smell free.

Benn

Benn

I have a Lectrasan on Nevia and when I fitted the holding tank I fitted a vent however there is more smell coming from the shower tank than from the toilet system

Allan

Peggy: What you say about wear on the impeller sounds a lot like, "don't think you can actually use that pump to self-prime, as you are wearing out the impeller if you do".
I tried self-priming when mine was just out of the box. It didn't even do it then, so I moved it to be level with the Holding tank outlet. problem solved.

I am considering replacing the tank with one that is installed above the water line, then for an at sea discharge, I can let gravity do the work, eliminating the above noted problems.