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Tank filling slower than normal


ShropsWindowCleaner

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Hi all. My 250 litre tank used to take 1 hr 45 mins to fill from empty. I built the set up in July last year. Now it takes around 2.5 hours. PPM is only 3PPM. I use a Merlin RO with sediment pre filter and a booster pump at around 85psi. This is my first set up so i’m not sure why it’s slowed? Is it the:

Resin?

Carbon filter?

Sediment filter?

Combo of all three needing changing?

 

Thanks in advance 🙋🏼‍♂️

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If you haven't changed any prefilters at all since last July then the whole lot will be knackered including your membranes 

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33 minutes ago, Iron Giant said:

If you haven't changed any prefilters at all since last July then the whole lot will be knackered including your membranes 

Checked membranes, they are fine. Thanks though 👍🏻

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11 hours ago, ShropsWindowCleaner said:

Checked membranes, they are fine. Thanks though 👍🏻

Not sure if you are part time or not, but on average very good pre-filters need changing every 2-3 months depending on water usage, sediment in the water etc. 

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On 17/03/2021 at 17:27, ShropsWindowCleaner said:

Hi all. My 250 litre tank used to take 1 hr 45 mins to fill from empty. I built the set up in July last year. Now it takes around 2.5 hours. PPM is only 3PPM. I use a Merlin RO with sediment pre filter and a booster pump at around 85psi. This is my first set up so i’m not sure why it’s slowed? Is it the:

Resin?

Carbon filter?

Sediment filter?

Combo of all three needing changing?

 

Thanks in advance 🙋🏼‍♂️

Firstly I'm no expert but I have a limited experience of the setup. 

If you are still feeding the system with the same amount of water at the same pressure then there is a blockage somewhere. 

Prefilters - if these haven't been changed then it may contribute to slight slowing but not much, there is far too much surface area within them to slow it unless they are completely satured with ****. 

Resin - resin will not slow water down, it just loses its ionic charge I think, but definitely won't slow water 

Ro - my guess would be your ro, if you don't flush regularly for at least 5 minutes each time your going to clog the minute pours that allow water through but catch the minerals.. Thats how small the holes are. 

Conclusion is to flush you membrane on fully open waste for a minimum 30 minutes to see if this improves, if not your membrane will still produce but will slow how quick it can produce. 

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1 hour ago, Baldmonkey said:

Firstly I'm no expert but I have a limited experience of the setup. 

If you are still feeding the system with the same amount of water at the same pressure then there is a blockage somewhere. 

Prefilters - if these haven't been changed then it may contribute to slight slowing but not much, there is far too much surface area within them to slow it unless they are completely satured with ****. 

Resin - resin will not slow water down, it just loses its ionic charge I think, but definitely won't slow water 

Ro - my guess would be your ro, if you don't flush regularly for at least 5 minutes each time your going to clog the minute pours that allow water through but catch the minerals.. Thats how small the holes are. 

Conclusion is to flush you membrane on fully open waste for a minimum 30 minutes to see if this improves, if not your membrane will still produce but will slow how quick it can produce. 

You can't flush a Merlin r/o.

I would certainly agree that the issue is possibly with the prefilters. I would remove the sediment filter first and see if that makes a difference. Then I would remove the carbon/sediment filter in the unit for a brief run to see if it improves. Then put the carbon block/sediment filter back before ordering a replacement.

The trouble with those Merlins is that you have to take them apart to inspect the internal prefilters. A sediment blocked prefilter will slow the water flow rate down which will affect production rates. Mine is doing it at the moment and I've still got 20,000 litres to go before a prefilter change. I'm going to have to change that sediment filter early.

 

Edited by spruce
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On 17/03/2021 at 17:27, ShropsWindowCleaner said:

Hi all. My 250 litre tank used to take 1 hr 45 mins to fill from empty. I built the set up in July last year. Now it takes around 2.5 hours. PPM is only 3PPM. I use a Merlin RO with sediment pre filter and a booster pump at around 85psi. This is my first set up so i’m not sure why it’s slowed? Is it the:

Resin?

Carbon filter?

Sediment filter?

Combo of all three needing changing?

 

Thanks in advance 🙋🏼‍♂️

I'm sorry but these Merlins weren't designed for window cleaner use.

They were designed around American kitchens as a third tap. They haven't the provisions we need to maintain an efficient filtration system. You can't flush the membranes or change prefilters individually. Increasing the tap water pressure does help with efficiency as you have done, but your long term solution is to replace it with a 4021 or a 4040.

What a Merlin does have is the provision to switch the tap off which stops the water flow through the r/o. So they work quite nicely with a ball float in the tank. IMHO the negatives outweigh the positives.

 

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5 hours ago, Baldmonkey said:

Prefilters - if these haven't been changed then it may contribute to slight slowing but not much, there is far too much surface area within them to slow it unless they are completely satured with ****. 

It depends a lot on where you are. Some locations have more sediment and will silt up a lot faster.

Even if its generally good though, if any major water works have been done recently nearby, they can be completely clogged within days. 

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Well I'll have to bow down to a superior knowledge. I can only comment on my area and what I would check first, but then again I change filters frequently and have a setup that allows me to rinse my ro membranes so wouldn't be in that predicament anyway 😂😂😂

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4 hours ago, spruce said:

You can't flush a Merlin r/o.

I would certainly agree that the issue is possibly with the prefilters. I would remove the sediment filter first and see if that makes a difference. Then I would remove the carbon/sediment filter in the unit for a brief run to see if it improves. Then put the carbon block/sediment filter back before ordering a replacement.

The trouble with those Merlins is that you have to take them apart to inspect the internal prefilters. A sediment blocked prefilter will slow the water flow rate down which will affect production rates. Mine is doing it at the moment and I've still got 20,000 litres to go before a prefilter change. I'm going to have to change that sediment filter early.

 

Changed the sediment filter and carbon filter today and everything is running a lot faster. Thankfully membranes are fine. Needed new resin too as water was up to 4PPM so changed that while i was at it. I’ve got a water meter between resin and tank now, so will change filters in accord with manufacturers recommendation. Thanks to @doug atkinsonfor the filters 👍🏻 Speaking of which @doug atkinson or @spruce, after how many litres would you recommend changing the filters again? Or is it like a cam belt where you change it after a certain period of time even if you haven’t made the litres? 

I will change to a better RO in time, but this is my first ever pure water system after buying water for some time. Only 10 months in and learning fast. 😁

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The Carbon Filter does 37,800 litres of water going through. However it may be less if Chlorine content is high.

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2 minutes ago, doug atkinson said:

The Carbon Filter does 37,800 litres of water going through. However it may be less if Chlorine content is high.

Thanks @doug atkinson. I probably won’t produce that amount in 6 months. Would you advise changing the filter after a certain period of time despite not getting to 37,800 litres? 

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20 minutes ago, ShropsWindowCleaner said:

Thanks @doug atkinson. I probably won’t produce that amount in 6 months. Would you advise changing the filter after a certain period of time despite not getting to 37,800 litres? 

Best change it every 6/7 months 

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41 minutes ago, ShropsWindowCleaner said:

Thanks @doug atkinson. I probably won’t produce that amount in 6 months. Would you advise changing the filter after a certain period of time despite not getting to 37,800 litres? 

It's not just what you produce mate, it's what runs through the system. I'm running at 65/35 currently so 10k litres of water only produces 3.5k (Damn thats a grim thought when I'm about to move to a new build with a water meter) Make sure you factor that in too.

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12 hours ago, ShropsWindowCleaner said:

Thanks @doug atkinson. I probably won’t produce that amount in 6 months. Would you advise changing the filter after a certain period of time despite not getting to 37,800 litres? 

The service life of a carbon block filter is dependant on all the water your r/o uses. This also includes water that goes to waste.

So if your r/o has a pure to waste ratio of 3 waste to produce 1 pure, that process has used 4 liters of water which has gone through your carbon block filter. The service life of your carbon block filter isn't governed by the amount of pure you use a day cleaning windows.

 

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12 hours ago, P4dstar said:

It's not just what you produce mate, it's what runs through the system. I'm running at 65/35 currently so 10k litres of water only produces 3.5k (Damn that's a grim thought when I'm about to move to a new build with a water meter) Make sure you factor that in too.

I thought you might have moved already, Can you have a sub meter fitted like @Pjj so as to only for the water you use and not the sewer charge for the waste water. 

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14 hours ago, P4dstar said:

It's not just what you produce mate, it's what runs through the system. I'm running at 65/35 currently so 10k litres of water only produces 3.5k (Damn thats a grim thought when I'm about to move to a new build with a water meter) Make sure you factor that in too.

I think the new PRF is set to a better pure to waste ratio than its older brother the Merlin was. A fellow windie in town has the old Merlin. This is the second one and both used around 6 litres of water to produce 1 litre of pure. (5 to 1).

Our water is soft to medium, so he put a gate valve on the waste to the drain pipe to throttle back his water going to waste. It was around 2 waste to 1 pure last time I spoke to him. He also added a stand-alone sediment prefilter to protect the more expensive Fiberdyne combo carbon/sediment filter used by the Merlins. From time to time we have a real problem with sediment in our water supply that clogs the sediment filters in days. It's cheaper to replace a sediment filter than the Fiberdyne filter.

 

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23 hours ago, spruce said:

This is the second one and both used around 6 litres of water to produce 1 litre of pure. (5 to 1).

Ouch!

On 20/03/2021 at 06:11, Iron Giant said:

I thought you might have moved already, Can you have a sub meter fitted like @Pjj so as to only for the water you use and not the sewer charge for the waste water. 

I think the biggest benefit with that is you get a separate bill so you can actually put it on your tax return without ever worrying. I'm gonna have the system plummed directly into the water supply so should be easy enough. I also plan to plumb the waste straight into the drain, or at least into the gutter.

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1 hour ago, P4dstar said:

Ouch!

I think the biggest benefit with that is you get a separate bill so you can actually put it on your tax return without ever worrying. I'm gonna have the system plummed directly into the water supply so should be easy enough. I also plan to plumb the waste straight into the drain, or at least into the gutter.

Its get even worse. The membranes were only around 90% efficient from new. So not only were the water costs high but so was resin costs. I believe that the membranes are better these days, but they didn't have to be as the Merlin only produced clean drinking water.

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At our last house we were getting fluctuations with water pressure throughout the day, I now produce overnight despite having much better water pressure at our new home. 

It will still take 12 hours or more for my 450gpd R/O to produce 350ltrs of pure, sediment seems also to be an issue since work was done in the last 1-2 years locally, we have an old lead pipe water supply pipe running to our house so not sure if that and old pipes under the concrete road which were installed in 1940 when the houses were built is a sediment issue or rust issue my sediment filter is browning up within 3-4 weeks 

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