Macerator Problems

[AndrewB]

We own a Hunter 410 (2000) and spend much time cruising and about 5 months (winter) in the Bahamas.
The original macerator (regular Jabsco 18590-2092) would not always pick up when the holding tank was almost full. When this happened we would have to remove the intake pipe from the macerator and put 2 or 3 cups of water down the pipe, reconnect the pipe quickly and then it would normally pick up and pump the waste out.

As you can imagine, this was some what unpleasant.

So we looked at the specifications for the pump and noted that the pump should lift water to 5ft. Our macerator is no more than 18” above the top of the holding tank. We then looked at the specifications for the Jabsco diaphragm waste pump 50890-1000 and noted that the spec for it was “Self-priming up to 10 Feet (3 m) vertical lift”.
So we purchased two of these units (Always need a spare) and had a new 1 ½ “ thru hull installed and installed the pump ……. With the expectation that our problems would be solved.
Again this diaphragm pump would occasionally not pick up. The root cause of the problem is that much of the waste floats in the holding tank and when it is pumped out the very last bits get left in the exit valve and wedge it open so that the unit is unable to create a vacuum and pick up the next time it is used. (See Photo)
Any suggestions other than chew more!

 

[Peggie Hall HeadMistress]

When, if ever, was the last time you flushed out the tank?

'Cuz unless your sink drains are going into the holding tank or you're disposing of something besides body waste and TP by dumping it into the toilet, or you're using gray water to flush...it's unlikely that anything remains floating in the tank. Solid waste is 75% water, is also broken up by the toilet pump, and therefore dissolves very quickly and settles to the bottom to become sludge. Toilet paper, even the wrong kind for use in marine toilet, settles to the bottom to add to the sludge. If you use a chemical tank product that kills bacteria, that sludge never breaks and emulsifies. And that, along with the occasional popcorn kernel and/or watermelon seed--neither of which float, is what I suspect is clogging up your pump.

Waste tanks should be thoroughly flushed out at least 2-3x/season. That's done by pumping out, then putting several inches of water into the tank via the deck pumpout fitting--'cuz that sends the water into the tank at the bottom to stir up sludge and hold it in suspension so it can be pumped out...pump that out. Repeat...repeat...till you're pumping out clean water. Do that, and it should solve your problem.

Better yet, install a Type I treatment device and eliminate the need to use a holding tank altogether. Herring Bay is the only "no discharge" zone in the whole Bay, making the discharge of treated waste from a CG certified device is legal everywhere else, not only in the Bay, but 99% of the whole east coast between the Bay and the Keys...and the discharge is cleaner than the discharge from most sewage treatment plants...in fact, cleaner than most of the waters it's going into. And certainly much more pleasant for those around you in an anchorage in Carribean than flushing raw waste overboard or worse yet, dumping a tank. Check out the ElectroScan and PuraSan here: Raritan Waste Treatment

 

[AndrewB]

Peg
Thanks for reply.
When we have to clean the senders (about 3 times a year) we put a hose into the holding tank and spray down with fresh water. We have even developed a attachment for the hose so that it can go down the hole for the sender and then turn up to spray the walls of holding tank.
When the macerator works we notice that as the tank is almost empty then the heavy duty solids come out ........ since the pick up is at the bottom of the tank we believe that stuff must be floating. We are now getting to the stage of pouring water down the pump out whilst the macerator is working in an effort to reduce that solid getting stuck in the valve........ Not easy to judge.
Your idea of the ElectroScan would be good if I had space to put it. Just no room.
Is there some chemical that would break up the solids?
Thanks in advance.

 

[Peggie Hall HeadMistress]

When the macerator works we notice that as the tank is almost empty then the heavy duty solids come out ........

That's because the heavy solids (sludge) is on the bottom of the tank. The accumulation isn't deep enough to cover the entire discharge fitting, so the pumpout or macerator can pull the liquids out till the level has dropped down to level of the sludge.

...since the pick up is at the bottom of the tank we believe that stuff must be floating.

Nope...What you're doing is only washing down the walls of the tank, it's not stirring up the sludge and putting it into suspension so it can be pumped out. If you'll do exactly what I described in my first reply--and stay with it till the only thing left in the tank is clean water, you'll solve your problem.

As for any chemical to break up the solids.. Plain water will do as much as ny chemical. I'll repeat what I said above: Solids are at least 75% water...going through the pump breaks 'em up...they dissolve in the tank in a very short time to settle to the bottom as sludge. NON-chemical tank products help waste to break DOWN and emulsify...chemical tank products kill all the bacteria needed to break down and emulsify solids and TP.

And replace that tank level indicator with a system that puts the sender on the outside of the tank! Check out the Profile gauges Profile Tank Monitors Top rated by Practical Sailor, and the best customer service on the planet. A whole bunch of people here have installed 'em and loved 'em.

You might want to check out the link in my signature below...it'll take you to a comprehensive "marine toilets and holding tanks 101" manual that should give you a much better understanding of how to maintain a system to keep it trouble free and odor free.

You do have room for an Electro Scan...I guarantee it. We just need to be a bit creative in locating it. I'll be glad to help you do that if you want to get with me privately via email (NOT a PM please!).