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Black Water Problem

Discussion in 'Technical Discussion' started by Hogfish, Apr 23, 2011.

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  1. Hogfish

    Hogfish New Member

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    Hey guys,

    Having trouble on a 60 Hatteras M/Y with the black water holding tank. Just hopped on board and the owner has told me that the tank will not pump past 50%. She had been sitting over a year before going on the hard where she currently rests. I believe there must be a great deal of sludge-like buildup that has accumulated. This week I plan on adding in a mix of water softener powder, laundry detergent, and bleach. Along with that I have ordered some enzymatic additive to toss in as well.

    Since the boats on the hard and I have yet to go off-shore and test out the O/B discharge, I was planning on letting that concoction sit for a few days, adding water periodically, and then eventually getting a pump-out truck to the boat. I figured I would pump the hold and then flush the entire tank multiple times with freshwater to see if I could get most of the crud out.

    Any suggestions or revisions to this game plan would be certainly appreciated! Also, I plan on using minimal bleach as I would like to avoid eating any weak seals...

    Thanks guys!
  2. Capt J

    Capt J Senior Member

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    Do NOT USE BLEACH. I would fill it with freshwater, pump the entire tank out, then just pull the pickup out of the tank and confirm how much waste has been pumped out. You can see inside the whole tank and inspect the pickup itself.
  3. K1W1

    K1W1 Senior Member

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    Hi,

    Do you know if the tank level measuring you are using is accurate?

    Adding bleach will kill any enzymes you want to add, enzymes generally take a few weeks to build up a reasonable base and to operate properly.

    There is no magic bullet as such with this type of thing save yourself some grief and headaches get a tank cleaning company in to water blast and clean the tank and then you can use FW while you figure out the level measuring and OB Pumping arrgts.
  4. Pascal

    Pascal Senior Member

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    How old is the boat? Older hatts used dip tanks that would corrode and eventually break off or develop holes preventing full pump out

    I ve never seen sludge be a real issue

    Firs make sure it s not a simple problem like weak vacuum from the pump out station (pretty common) or a clogged vent which causes a vacuum to build in the tank until the pump can't overcome it
  5. Capt J

    Capt J Senior Member

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    I agree and also have neveer seen sludge as an issue. Also the Hatteras pickup is part of a plate that bolts to the tank and when unbolted and taken out leaves approximately a 8"x10" opening in the top of the tank......I have also had the very same problem on a 58' Hatteras and it was indeed the pickup.
  6. Hogfish

    Hogfish New Member

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    Thanks for the replies guys, I really appreciate it!

    Here is where I am currently at:

    The new system is a Headhunter system that replaced the pre-existing toilets and plumbing on an '89 Hatteras. From what I saw today, there is a Mach 5 F/W pump, leading to a Well-X-Trol pressure accumulating tank that splits into a freshwater feed and then toilet feed.

    I traced the new Headhunter toilet hoses starting with the Aft Master stateroom. The line runs and then joins with the VIP head, also on the starboard side. They run through the bilges and into the Aft end of the generator room beneath the galley floorboards.

    The forward Crew's quarter head line runs aft along the port side and then joins with the other two heads hoses where all three discharge into the tank. The hoses look great and have solid PVC connection points where each line intersects. All hoses appear to be about 2.25" in diameter.

    The boat has been on the hard for about 2.5 months while undergoing a major refit. (Just stepped on board) Part of this refit included the installation of new Onan gensets. I do not know if the guys installing the new generators have disconnected some of the hoses temporarily while installing or if the original job was never fully completed. Here is where it starts to become interesting...!

    From the heads to the holding tank, the feed looks great. However, all of the old hoses have been disconnected and the old fittings have not been capped.:eek: Along with that, there is a large fitting in the center of the tank. It stands tall and looks similar to a seacock without a lever. On the side of it, a very long Headhunter line has been connected and it runs to the exterior starboard vent. (The line also has a coil that rests on the generator floor that is probably adds an extra 6 feet to the vent so I imagine it was temporary) At the very top of the fitting, it appears that the end cap is removable to serve as a very small sight gauge. I could not open it as the new PVC from the aft staterooms runs across it and I did not have enough time to take it apart yet.

    Coming out of the tank is another Headhunter hose that has a massive check valve on it. It stops about 3 feet or so shy of a Mako diaphragm pump that has been set and wired but not connected to the discharge. This obviously appears to be the O/B discharge, but I do not see which seacock whoever was installing the system intended to use, nor is there a hose leading to one. There are three nearby seacocks that are all in use. I guess I could tap into one, splitting the line... I understand how all of this ties in, just flabbergasted as to how it all ended up this way! A bit confusing to me. I am waiting to hear back from the person who installed the system, or was in the process of installing sounds more like it. I plan on checking with the yard tomorrow as well.

    Sorry about the long post, don't think I could have made it much shorter! Time for a beer. :eek:

    Thanks guys.
  7. Hogfish

    Hogfish New Member

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    Man, definitely did not see a bolted plate. That sure would be nice! I'm guessing the pickup must be intact because a new one has been installed. However, judging by how everything looks right now, that could probably be all eff'ed up as well...
  8. Capt Bill11

    Capt Bill11 Senior Member

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    "However, all of the old hoses have been disconnected and the old fittings have not been capped."

    Obviously they need to be capped properly.

    "Along with that, there is a large fitting in the center of the tank. It stands tall and looks similar to a seacock without a lever. On the side of it, a very long Headhunter line has been connected and it runs to the exterior starboard vent. (The line also has a coil that rests on the generator floor that is probably adds an extra 6 feet to the vent so I imagine it was temporary)"

    I would shorten and make that hose run as straight as possible. If you can get good clean air flow into a holding tank you can promote the growth of aerobic bacteria and there by eliminate odors from the tank. In fact having 2 vent lines, one going to each side of the boat, is even better.
    Otherwise you may need to install an inline vent filter which you can make yourself.

    "At the very top of the fitting, it appears that the end cap is removable to serve as a very small sight gauge. I could not open it as the new PVC from the aft staterooms runs across it and I did not have enough time to take it apart yet."

    I don't think I'd bother much with opening it. Make sure it's sealed well and get a good tank monitor and be done with it. Unless of course you can use it as the access port for the monitor.

    "Coming out of the tank is another Headhunter hose that has a massive check valve on it."

    Not sure what the point of the check valve is. You would be better served by having a ball valve there that you can lock off some how to show the USCG if you get stopped and inspected.

    "There are three nearby seacocks that are all in use. I guess I could tap into one, splitting the line"

    Bad idea. The black water over board should have it's own thru hull.
  9. casec11

    casec11 New Member

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    [[["Coming out of the tank is another Headhunter hose that has a massive check valve on it."

    "Not sure what the point of the check valve is. You would be better served by having a ball valve there that you can lock off some how to show the USCG if you get stopped and inspected."
    ]]]

    The purpose of the check valve is for the diaphragm pump. In case a solid keeps the check valve on the pump from closing there should be another check valve on the discharge and inlet side of the diaphragm pump about 3 feet in either direction.
  10. Danvilletim

    Danvilletim Member

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    We are also experiencing that we can't pump below 50% o/b. At the pump out on Sunday we got to 10% but jumped back up to 40% by the time we docked. How can you test if the air vent is free? How can you test if pick up is clogged?
  11. Dave Stranks

    Dave Stranks Member

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  12. cdg

    cdg New Member

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    I have a similar problem, perhaps. I have Headhunter system with 200g black water tank that is treated with an ozone stream. After pumping out the black water (I do probably overdo the frequency, as I can't imagine having an overflow!) a constant stream of bubbles suggested the tank was drained. The gauge is not working - one says 0% all the time and the other stays on a reading of 2749g. Next thing, the heads start bubbling (non smell from bubbles), and the bidet let in a brown solution (treated, but definitely black water) via its plughole. Inspecting the overboard drain... I noticed that the "inverted U bend" of hose (the drain is below the waterline) didn't seem to have fluid inside, except near the bottom of the "up" side of the U. Could I have an air lock? What els eis stopping the pump pushing the black water overboard? The pump is Sealand ("TW?") pump is pumping away happily - but it does not drain the black water overboard.
    (And btw the U bend seems to be attached via a new tube, to an empty, new PE tank (which Headhunter Inc site seems to show as a chlorine dispensing tank... but I use ozone....anyway... no idea what that's about!).
    Thoughts anyone about a) how I should best clear the black water without incident and b) how I might avoid the air lock in future (if that is the only barrier to the drain working).

    Many thanks in advance!
  13. K1W1

    K1W1 Senior Member

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    Check that your tank does not have blocked vents. Can you see anything being pumped out when you run the pump?
  14. cdg

    cdg New Member

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    Thanks K1W1. Nothing comes out when pump is running. The vent is through the upper decks, exiting at roof. It was gurgling too... so, I'm guessing only, it's not a blocked vent.
  15. K1W1

    K1W1 Senior Member

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    Can you determine if there is actually anything in the tank?
  16. cdg

    cdg New Member

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    Yes there is cos I've had 6 people aboard for a week!
  17. K1W1

    K1W1 Senior Member

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    Is there anyway you can use a water hose and try to push some fluid back down the line from the pump inlet to the tank? The suction might be blocked especially if some of those guests have been women who have dropped their sanitary surfboards etc down the toilet and flushed it
  18. cdg

    cdg New Member

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    I can feed a hose into the OB drain hole and blast some water in there? I was worried about upsetting some delicate balance if I did that .....and btw the pump inlet comes from a pressurised header tank.
  19. K1W1

    K1W1 Senior Member

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    I am not familiar with your exact system but am familiar with a lot of pumps and tanks.

    How does the header tank get pressurised?

    How does the tank contents get from the tank to the header tank?
  20. cdg

    cdg New Member

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    cdg: Apologies may have misled you! Here is the system described: The fresh water is pressurised in header tank... that feeds the heads...the heads flush with tough button activated Headhunter Royal flush system.... waste drops to MSD for ozone treatment... black water tank fills.. black water vents through roof of pilot house.... I manually discharge black water OB* as required (Sealand pump on top of black water pumps via that U bend tube over board.
    *I could also mention the the PE box I mentioned above appears (um...haven't traced whole line yet as it requires many panels to come off) to have a tube that connects it to the top of that U bend just above the discharge outlet - but perhaps thats just from an old chlorine treatment system (which I read from previous skipper's notes was replaced by the current ozone treatment).

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