Watermaker Brine Discharge

[noelex 77]

Watermaker brine discharge
I am in the process of installing a Spectra 150. I have discovered the brine discharge seacock used by the old watermaker, that I was planning to use for the new system, has a alight leak when open. This is only just above the waterline and will be messy to replace in the water.
I have an unused underwater discharge of suitable size that would be much easier to use at least until the next hall out.
Is there any problems using a below water discharge for the brine outflow? Will it create more backpressure?

[senormechanico]

I imagine it would give you any problems.
BTW, I have a Spectra 180.
Great unit, much better than the two other brands I installed in a previous boat.

[Jentine]

The brine is under sufficient pressure that it will cause no problems. I have my discharge below the water line and have had no problems for more than two years.

[Albro359]

Ditto...mine goes out below the waterline... no issues..

[Tellie]

A few things to consider. Is this a Ventura 150D or MPC5000? Back pressure should not be much of an issue to the water maker itself. The problems with under water thru hulls is they get blocked by growth. If you fail to keep the thru hull clear the Clark pump can easily create enough pressure at the brine discharge to eventually blow a hose off at the clamps or burst a weakened hose or fitting. If you have the MPC5000 the unit will start itself every 120 hours of non use, under pressure, usually when you are not around. What you should also consider is the location of the install. Will the Clark pump be mounted above or below the water line? A 150 feed pump is not supposed to be more than 36" above the water line. If below the water line, the plastic quick disconnect on the Clark pump is the weakest link between an under water thru hull and a open under water hose inside your boat. It doesn't take much of a bump to break these off at the threads. I would hope that the thru hull has a shut off valve. I'd keep it closed when not in use and only run the water maker while you are on board. A good reason to have a brine discharge just above the water line is to have a quick visual of what's happening with the water maker as it's running. You'll get used to how and to the amount of brine water that should be coming out under normal operations with a quick glance over the side. I have to say this. Spectra, nor myself would never, ever, promote or approve a under water brine discharge installation. But it is your boat and a under water thru hull will work temporarily with good visual vigilance. But it is far less than desirable and I would suggest a new proper above the water line thru hull now or at the least when you haul out.

[Albro359]

, the plastic quick disconnect on the Clark pump is the weakest link between an under water thru hull and a open under water hose inside your boat. It doesn't take much of a bump to break these off at the threads

Sounds like a good reason to buy something else that's better engineered !!

[Tellie]

Originally Posted by Albro359

, the plastic quick disconnect on the Clark pump is the weakest link between an under water thru hull and a open under water hose inside your boat. It doesn't take much of a bump to break these off at the threads

Sounds like a good reason to buy something else that's better engineered !!

Actually, it's a good reason to install them correctly

[Albro359]

the plastic quick disconnect on the Clark pump is the weakest link between an under water thru hull and a open under water hose inside your boat. It doesn't take much of a bump to break these off at the threads

What sort of IDIOT would design something that had a PLASTIC QUICK DISCONNECT on a hose connected to a thruhull ???

Proper hose connectors and double hose clamps thanks !!!

You want to sink ????

[Tellie]

Originally Posted by Albro359

the plastic quick disconnect on the Clark pump is the weakest link between an under water thru hull and a open under water hose inside your boat. It doesn't take much of a bump to break these off at the threads

What sort of IDIOT would design something that had a PLASTIC QUICK DISCONNECT on a hose connected to a thruhull ???

Proper hose connectors and double hose clamps thanks !!!

You want to sink ????

I'll refrain from the name calling. Boat systems including water makers are designed to be installed properly. Giving advice or suggesting to others short cuts or anything other than a proper install does not make the system faulty or unsafe, the advice and improper installation does. It is very clear in the instruction manual that the brine discharge is to be placed above the water line. The OP or any owner that decides to ignore any of his boats systems provided installation information is assuming his own risk.

[noelex 77]

Thanks everyone for the replies. I really appreciate the advice.
I understand there is no technical problem with the brine discharge below the waterline, other than the risk of sinking the boat!
The unit is not an MPC and I would not operate the watermaker (or other machinery) while not on board. The clark pump is above the waterline with the hose well secured so there is no risk of a siphon if the quick disconnect fitting became dislodged or broke.

Incidentally so far I am very impressed with the unit it is very well made and arrived with all fittings even hose clamps. So far it has made 400L water in 3 days of operation all from solar power. I will provide a more detailed account when I have sorted out the installation properly and it has been running longer.

[syoder]

I installed my Spectra 150 brine discharge above the water line. One good reason to do it is to be able to monitor the flow for troubleshooting purposes and just to see if it's doing what it's supposed to be doing.

-Steve

[noelex 77]

Originally Posted by syoder

I installed my Spectra 150 brine discharge above the water line. One good reason to do it is to be able to monitor the flow for troubleshooting purposes and just to see if it's doing what it's supposed to be doing.

-Steve

Thanks Steve.
I think above the waterline is best place, but it will be easier to move mine to below the waterline, until the next hallout. The instruction manual also recommends monitoring the discharge. I cannot quite work out why this is important. The meter provides a measure of product output. If the product output and pressure are normal the unit must be discharging. This even applies when doing a freshwater flush.
The Spectra is new to me, but I cannot see a fault that would be obvious looking at the brine discharge that would not be apparent from the meter(or maybe the bilge alarm if the discharge line broke).
If you want to analyze the discharge closely ( to measure volume, or ppm at the end of a flush for example) then the discharge is easily diverted into a bucket.
As I have only just got the Spectra perhaps I am missing something.

[Tellie]

Originally Posted by noelex 77

Thanks Steve.
I think above the waterline is best place, but it will be easier to move mine to below the waterline, until the next hallout. The instruction manual also recommends monitoring the discharge. I cannot quite work out why this is important. The meter provides a measure of product output. If the product output and pressure are normal the unit must be discharging. This even applies when doing a freshwater flush.
The Spectra is new to me, but I cannot see a fault that would be obvious looking at the brine discharge that would not be apparent from the meter(or maybe the bilge alarm if the discharge line broke).
If you want to analyze the discharge closely ( to measure volume, or ppm at the end of a flush for example) then the discharge is easily diverted into a bucket.
As I have only just got the Spectra perhaps I am missing something.

Being able to give a quick glance over the side to see the brine discharge is usually a lot easier than heading down below to monitor the pressure gauge and flow meter. You will get a "feel" for how things are working with your water maker by observing the brine discharge. You will soon be able to tell if the Clark pump is shifting symmetrically, if the 5 Micron pre-filter is fouling by the amount of flow. The brine flow will not be constant. It will drop off every six or so seconds as the Clark pump shifts. Variations of this shift timing can tell you conditions of the pump as well.

[NoTies]

Originally Posted by Albro359

What sort of IDIOT would design something that had a PLASTIC QUICK DISCONNECT on a hose connected to a thruhull ???

Proper hose connectors and double hose clamps thanks !!!

You want to sink ????

The same sort of person that designs just about any whale/jabsco/johnson etc electric washdown pump, any water lubricated dripless shaft seal, any non metallic sea strainer. Look to your own installations before flaming others here. Unless your boat is designed like a battleship you will have numerous vulnerabilities that need to be mitigated through proper installation or vigilance. About 2 hours ago I finished a membrane clean on a spectra and have done a couple of pump rebuilds and I am impressed by the quality of engineering.

[noelex 77]

Originally Posted by Tellie

Being able to give a quick glance over the side to see the brine discharge is usually a lot easier than heading down below to monitor the pressure gauge and flow meter. You will get a "feel" for how things are working with your water maker by observing the brine discharge. You will soon be able to tell if the Clark pump is shifting symmetrically, if the 5 Micron pre-filter is fouling by the amount of flow. The brine flow will not be constant. It will drop off every six or so seconds as the Clark pump shifts. Variations of this shift timing can tell you conditions of the pump as well.

Thanks Tellie great reply. That all makes sense.
In my centre cockpit boat the guage is actually easier to see than the above water seacock discharge as the curve of hull means you have to lean out to see the flow of water, but I understand the brine discharge flow can provide some helpfull extra information..