Flushing a Spectra water maker?

[mestrezat]

I just had dinner with a fellow cruiser and he tells me he only back flushes his water maker(not a Spectra) if he is not going to use it for more than a week or so. Unless I'm mistaken, I think my manual for Spectra says to flush it after every use. Am I overdoing it by flushing it after every use? Mine makes only 8 gallons and hour so flushing it takes just about an hours worth of production.

[colemj]

8 gallons is a lot for flushing - are you sure it uses that much?

On our old 6gph watermaker, we only flushed it if we were not going to use it for more than 3-5 days (environment dependent). We never had a problem operating like this.

On our new 30gph, we flush after every use simply because we have the extra water. However, I don't think we use more than a gallon or two to flush.

Mark

[mestrezat]

In reading the owners manual, it says to run it in flush till the pressure drops to (can't remember which)2000 or 200 pounds. That takes a couple of minutes,all the while it's pumping at full pressure fresh water through to unit. With that pressure, it adds up. It only makes 8 gallons per hour, but it has to pump a bunch of water to get it. That's why I was wondering about the flushing waste.

[TacomaSailor]

We flush our Spectra 380c ( dual feed pump nominal 17 GPH installed in spring 2000) for about 60 - 90 seconds (about 3 gallons of freshwater) after each session of making water. That time corresponds with the pressure drop another respondent mentioned. When the system is full of freshwater the Clark Pump reverses at 25 psi with two feed pumps running and 20 psi with one feed pump.

If we are going to leave the Spectra unpickled and unused for more than five days we would flush for about 3 minutes (6 gallons or so). We have left the Specta full of fresh water, unpickled, after a 6-minute flush for 3-weeks with no problems.

The original membrane installed in July 2000 is still working pretty well. We make 15 GPH of 275 ppm fresh water in 63 degree sea water at 14.1V.

[2Hulls]

Originally Posted by TacomaSailor

We flush our Spectra 380c ( dual feed pump nominal 17 GPH installed in spring 2000) for about 60 - 90 seconds (about 3 gallons of freshwater) after each session of making water.

We have a 380c as well and run it every day in the tropics for at least 30 minutes without a product water flush afterwards. On occasion we do a flush when we know we won't need to run it for up to 5 days.

There are obviously as range of approaches...

2 Hulls Dave

[Kenomac]

Spectra 380c here. We make water every day that we can. If in a harbor for more than 3 days I'll flush with fresh water, otherwise no flush.

[Dulcesuenos]

If you had an automatic spectra such as a mpc3000 or 5000 the auto flush cycle flushes the system every 5 days for 2.5 gallons, doing it every day is overkill on both manual or automatic systems

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[belizesailor]

Originally Posted by Dulcesuenos

If you had an automatic spectra such as a mpc3000 or 5000 the auto flush cycle flushes the system every 5 days for 2.5 gallons, doing it every day is overkill on both manual or automatic systems

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And the parameters of the flush cycle are programable so you can tweak it to your situation. For the MPC 3000 you need software to do this, but the MPC 5000 is programmable from the control panel...though not quite as easy to use as the software.

[mestrezat]

I'm running the Ventura Tropical 200 Deluxe that's made for warm water since we'd planned on doing the tropics(currently in Phuket, Thailand). The water is about 80 degrees. When we run the water maker, we typically run it for about 3 hours or for however we are running the generator. Our manual tells us to"turn on the fresh water flush valve and close the service valve". "Flush for 2.5 minutes or until the pressure drops on the gauge indicating the membrane is flooded with fresh water. Stop the flush". From that statement, I'm thinking they want it flushed after each use not every 3 or 4 uses which if far more practical. I tend to use it on passages but not as often as I should since we hold 270 gallons of water and that gets us through most passages but when I need it,I want to be sure she runs.
From the responses so far, few flush theirs every time especially if it's going to be used regularly. I' hate to screw up the membrane after 5 years of good service just tot save a few gallons of water.

[SV THIRD DAY]

With things like this, rather than just give a "because the manual says" or "that's what I've been doing", I think it's best to go straight to the answer of WHY. If you understand the reason of WHY you need/want/do a fresh water flush then you can decide if you need to or not.

Why are you doing a fresh water flush anyway?

To set the stage, Spectra, Cruise RO, HRO, Village Marine, (insert your company name here) can all sit in sea water almost indefinitely without hurting the parts or membrane. The reason for a fresh water flush is not to flush the sea water out of the system...it is the Sea Creatures (Plankton, bacteria, the animals) living in the sea water that need to be flushed out. The Why is biological organisms, not sea water.

What happens when the water maker (or any sea water water system for that matter) is left to sit is that the animals grow, reproduce and use all the oxygen up in the water. The animals then die and rot and are eaten by anaerobic bacteria. The Anaerobic bacteria then give off Hydrogen sulfide (H2S) gas and then we recognize that as the classic rotten egg smell. Do this all the time and their dead bodies can basically clog up your RO Membrane.

So how long does it take for these animals to grow out of control, take over your system and then die and rot? Well it varies of course with temperature and the concentration of sea creatures. In crystal clear water with little biological growth in cold climates, you can go much longer than fertile warm climates with plenty of animals in the sea water. Typically, this is a 4-10 day window. So most water maker companies say that the unit either needs to be ran or fresh water flushed every 5-7 days. That's what our manual says.

Now our manual says that you should fresh water flush after each run...but do I do that to my unit? No, not when I know I'm going to be making water again within 48hrs. I just turn it off and walk away. Done. But here's the catch. If I forget to make water again within 48hrs, by leaving all those animal bodies in the system I'm really increasing the chances for the animals to grow like crazy because now I didn't flush them out! So to play it safe, we put in our manual to fresh water flush after each run, because I'm on the hook for a 3-yr membrane warranty! But on my own unit, where I'm covering my risk anyway, I'm happy to skip the fresh water flush after each run and trust myself to run it again in 48hrs.

For me in tropical climates where we all want to be, I like the 4 day interval and that that is what we set-up our Automatic Fresh Water Flush option as the default. (I know what you are asking, "Rich, you are the no electronics guy...you have a fresh water flush option you hypocrite!" Well, heck I'm also a capitalist and if the client wants it as an option, who am I not to give the client what he wants!)

Just one more little comment, since I'm three fingers into my rum spritzer tonight. You commonly hear people talk about doing a "back flush" but in most water makers you are not reversing the flow of water through the system but simply flowing fresh water in the same direction the sea water would flow. Yes there are some systems out there that did reverse flow, but that's more old school and just not needed, so it's easier to swap the sea water flow for fresh water.

[Bulawayo]

We have a Spetra 200T which runs every day - and we have programmed the controller to flush the system every third day - to clean out any nasties that potentially could be within the system.

[Tellie]

Originally Posted by mestrezat

I'm running the Ventura Tropical 200 Deluxe that's made for warm water since we'd planned on doing the tropics(currently in Phuket, Thailand). The water is about 80 degrees. When we run the water maker, we typically run it for about 3 hours or for however we are running the generator. Our manual tells us to"turn on the fresh water flush valve and close the service valve". "Flush for 2.5 minutes or until the pressure drops on the gauge indicating the membrane is flooded with fresh water. Stop the flush". From that statement, I'm thinking they want it flushed after each use not every 3 or 4 uses which if far more practical. I tend to use it on passages but not as often as I should since we hold 270 gallons of water and that gets us through most passages but when I need it,I want to be sure she runs.
From the responses so far, few flush theirs every time especially if it's going to be used regularly. I' hate to screw up the membrane after 5 years of good service just tot save a few gallons of water.

Listen to me, flush your system after each use and every five days if you are not using it. If you use 2.5-3 gallons of fresh water to flush your 200T Deluxe then that's enough. Especially if you are using it often. You definatly want to flush it after every use even if you are using it often. As Rich points out above, planning on running your watermaker two days later is fine but things happen, it strecthes into a longer period of time of not using your watermaker and things go bad quickly. The tropics is a very good place to flush your watermaker after each use. Anyone who has ever had a salt water flushing head can tell you it doesn't take long at all for the stink, hydrogen sulfide, to appear, many times within a day or so. This is the same thing that happens in a watermaker.
Timing your fresh water flush time by a standard 2.5 minutes doesn't always work and neither does watching for the pressure drop on either manual units like yours or fully automated systems. For you it's a simple thing to figure out. Break out your brine discharge pickling hose and attach it to the Clark pump. Route the hose into a five gallon bucket. Start the system and time how long it takes to fill 2.5-3 gallons of water into the five gallon bucket. This is now the real time you flush your system for. These systems count on the house pressure pump to supply the watermakers fresh water flush side. These pumps come in all sizes, pressures and flows so every systems fresh water flush times will be different even with identical watermakers in different boats.
Also five years on a well taken care of 21" membrane is not old. I find the 21" membranes far out last the longer 40" membranes. But each membrane is going to be different. I've seen them last for 14+ years (rarely) and I've seen new ones fail in a less than a year (rarely). But on average 5-8 years is a good life span.

www.HaldenMarineService.com

[Dave852]

Originally Posted by SV THIRD DAY

With things like this, rather than just give a "because the manual says" or "that's what I've been doing", I think it's best to go straight to the answer of WHY. If you understand the reason of WHY you need/want/do a fresh water flush then you can decide if you need to or not.

Why are you doing a fresh water flush anyway?

To set the stage, Spectra, Cruise RO, HRO, Village Marine, (insert your company name here) can all sit in sea water almost indefinitely without hurting the parts or membrane. The reason for a fresh water flush is not to flush the sea water out of the system...it is the Sea Creatures (Plankton, bacteria, the animals) living in the sea water that need to be flushed out. The Why is biological organisms, not sea water.

What happens when the water maker (or any sea water water system for that matter) is left to sit is that the animals grow, reproduce and use all the oxygen up in the water. The animals then die and rot and are eaten by anaerobic bacteria. The Anaerobic bacteria then give off Hydrogen sulfide (H2S) gas and then we recognize that as the classic rotten egg smell. Do this all the time and their dead bodies can basically clog up your RO Membrane.

So how long does it take for these animals to grow out of control, take over your system and then die and rot? Well it varies of course with temperature and the concentration of sea creatures. In crystal clear water with little biological growth in cold climates, you can go much longer than fertile warm climates with plenty of animals in the sea water. Typically, this is a 4-10 day window. So most water maker companies say that the unit either needs to be ran or fresh water flushed every 5-7 days. That's what our manual says.

Now our manual says that you should fresh water flush after each run...but do I do that to my unit? No, not when I know I'm going to be making water again within 48hrs. I just turn it off and walk away. Done. But here's the catch. If I forget to make water again within 48hrs, by leaving all those animal bodies in the system I'm really increasing the chances for the animals to grow like crazy because now I didn't flush them out! So to play it safe, we put in our manual to fresh water flush after each run, because I'm on the hook for a 3-yr membrane warranty! But on my own unit, where I'm covering my risk anyway, I'm happy to skip the fresh water flush after each run and trust myself to run it again in 48hrs.

For me in tropical climates where we all want to be, I like the 4 day interval and that that is what we set-up our Automatic Fresh Water Flush option as the default. (I know what you are asking, "Rich, you are the no electronics guy...you have a fresh water flush option you hypocrite!" Well, heck I'm also a capitalist and if the client wants it as an option, who am I not to give the client what he wants!)

Just one more little comment, since I'm three fingers into my rum spritzer tonight. You commonly hear people talk about doing a "back flush" but in most water makers you are not reversing the flow of water through the system but simply flowing fresh water in the same direction the sea water would flow. Yes there are some systems out there that did reverse flow, but that's more old school and just not needed, so it's easier to swap the sea water flow for fresh water.

I think that was very helpful, the folks with smaller water makers running them every day or so can benefit greatly from that wisdom.


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[pjbar]

Hi All,

I have a crack in the centre block of my Spectra Ventura 150 watermaker. Whilst I have ordered a replacement block, I heard the other day that one can fix these cracks with superglue. Does anyone have experience and knowledge as to what the best adhesive would be to use?

Thanks for any help...

[belizesailor]

Originally Posted by pjbar

Hi All,

I have a crack in the centre block of my Spectra Ventura 150 watermaker. Whilst I have ordered a replacement block, I heard the other day that one can fix these cracks with superglue. Does anyone have experience and knowledge as to what the best adhesive would be to use?

Thanks for any help...

Really...where did you here that?