SpectraPure Help

[gsgentry]

I have one of the refurbished SpectraPure MPDI-90 systems that I bought a while back. Recently I noticed some diatoms on the sand after a huge water change. Went and tested my RO/DI water and I am reading 3ppm, so that explains what I am seeing in the tank.

 

I would guess that I have only made 300-400 gallons out of this unit. I purchased it 3/3/2014 and the color changing DI has only dropped maybe 1/2" at max, under the indicator sticker that they put on the tube.

 

Questions is, do I need to replace the membrane already? I can see and tell I need a new sediment and carbon filter, but I am not sure these can cause the 3ppm that I am getting.

 

Any help on this is great!! Thanks as always!!

 

 

 

[HarryPotter]

What is the TDS of the tap water you are putting into it?

[gsgentry]

My tap water is 305ppm.

 

The output of the RO/DI water has always been 0 until recently.

 

Thanks.

[rturiak]

Have you flushed the RO membrane? It can help with TDS creep

[markalot]

You need to check the TDS of the water leaving the membrane prior to the DI filter (not the waste, you will have to disconnect a blue hose to test).

 

Sediment -> Carbon block -> RO Membrane -> DI filter -> output

 

Waste water (yellow hose) also comes out of the RO membrane.

 

You should be replacing your Sediment and Carbon Block every 6 months or so to protect the RO membrane.

 

If TDS out of the membrane is reasonable (< 5 TDS) then most likely you have a co2 issue. Spectrapure has some FAQ's about testing for CO2 and solving CO2 issues.

[gsgentry]

I tested the water coming out of the membrane and it was 64 the first time. I collected a new sample and tested it again and it was 16. So I collected another sample and tested again and it's 11 now.

 

I don't have a flush kit on this unit, so I haven't flushed the membrane. Is there any way to flush it without the kit?

 

Thanks guys!

[gsgentry]

Ok I just watched the video on the flush valve and how it works. That being said, I removed my flow restrictor and I'm currently running the system, which is essentially what the flush kit does. I'll let it run for a bit and then test everything again. I'll post my results.

 

Thanks!

[AZDesertRat]

Don't waste money on flush kits. What you are seeing from the membrane is called TDS creep and flush kits do nothing for this, or anything else really other than to give you a warm fuzzy feeling.

What you need is a DI bypass. It can be as simple as a 1/4" tee and ball valve or a little more elaborate like a 3 way ball valve. It installs between the RO membrane and the DI filter and you open the valve, sending the initial bit of RO water to the drain each time you make water so the TDS creep on the treated side of the membrane doesn't exhaust the DI.

 

TDS creep happens with all membrane systems. When you shut the system off after making water, the tap water on the waste side of the membrane osmoses or is attracted by the low TDS, treated water on the treated side until it equalizes. The DI bypass flushes this out when you start the system again and you shut the bypass of once you see the TDS drop to your normal RO only level. Flush kits are on the waste side and do nothing for this since they only flush the waste side with more high TDS tap water.

[gsgentry]

Great information!

 

I ran it for an hour before reading this and it's 11 coming out of the membrane now and 2 coming out of the DI.

 

Do I need a new membrane at this point?

[gsgentry]

When you shut the system off after making water, the tap water on the waste side of the membrane osmoses or is attracted by the low TDS, treated water on the treated side until it equalizes. The DI bypass flushes this out when you start the system again and you shut the bypass of once you see the TDS drop to your normal RO only level.

 

If I understand this correctly, couldn't a simple on/off valve be placed on the waste line which would ultimately prevent the waste water from coming back into the membrane, thus keeping the membrane cleaner and keeping this water out of the DI. Granted, the water between the membrane and valve would have the potential to attract back.

[AZDesertRat]

No, the waste line should never have anything on or in it except the flow restrictor. The waste line should not have nay backpressure on it to cause a backflow. It hould dump into an open drain or other place such as landscape as long as it has an air gap to prevent a backsiphon in case the source were cut an a vacuum created.

 

The waste line where you install a flush kit and the treated line where you install a DI bypass are two different things.

 

If your tap TDS is 305 and your RO only TDS is 11 then your rejection rate or removal efficiency is 96.4% which is not bad but could be a little better. If you have made 300-400 gallons on the original DI then you have done well. A simple rule of thumb says a pound of DI resin will treat 3000 to 6000 total TDS. You have a 20 oz. DI filter so add 25% to that 3000-6000. 300 gallons x 11 TDS = 3300, 400 gallons x 11 TDS = 4400. The total TDS will be a little less too if you do not have a DI bypass valve sunce you are sending that initial TDS creep you saw (64, 16 etc) into the DI on start up. With a DI bypass you can flush that high TDS to the drain and greatly extend DI life.

[gsgentry]

Ok gotcha!

 

So do you think I need a new membrane at this point? Water coming out is 11ppm and water out of DI is still 2ppm.

[jamescstein]

Don't waste money on flush kits. What you are seeing from the membrane is called TDS creep and flush kits do nothing for this, or anything else really other than to give you a warm fuzzy feeling.

What you need is a DI bypass. It can be as simple as a 1/4" tee and ball valve or a little more elaborate like a 3 way ball valve. It installs between the RO membrane and the DI filter and you open the valve, sending the initial bit of RO water to the drain each time you make water so the TDS creep on the treated side of the membrane doesn't exhaust the DI.

 

I purchased the flush kit with my Spectrapure unit. However, I installed it as a DI bypass instead of how Spectra Pure recommended. Didn't want another hose to deal with.

 

I ran it for an hour before reading this and it's 11 coming out of the membrane now and 2 coming out of the DI.

 

Do I need a new membrane at this point?

 

Your DI must be exhausted or damaged. It should be able to drop 11 down to read 0.

[AZDesertRat]

If you installed a flush kit as a DI bypass, did you remove the flow restrictor or plumb it differently? Not sure what you mean by another hose to deal with? The DI bypass should exit to a drain.

 

I would not replace the RO membrane at this time, it is still performing at better than 96%.

What is your water pressure, water temperature, water hardness and your exact measured waste ratio? You may not have your waste ratio set correctly for your water conditions which could reduce the membrane efficiency.

 

Your DI is exhausted, we have already established that. If your sediment and carbon block filters are older than 6 months they also need replacing and the system needs it annual disinfection if that has not been done.

[jamescstein]

If you installed a flush kit as a DI bypass, did you remove the flow restrictor or plumb it differently? Not sure what you mean by another hose to deal with? The DI bypass should exit to a drain.

 

The flush kit didn't come with a flow restrictor so its just set up to go around the DI and discharge into the clean water pipe. After running it around the DI until the TDS reads its lowest, usually about 8 I then let it run through the DI for about a minute to clear the line.

 

As for another hose... my RO/DI waste line isn't plummed into a drain it has a suction cup attached that I stick to the side of my sink when I run the RO/DI.

[gsgentry]

Tap Water is 305

Water from membrane is 11

Water from DI is 2

Tamp Water Temp approx 77 degrees

Water pressure is approx 62 psi

Water from system is 220ml per minute

Waste Water is 920ml per minute (with current flow restrictor installed)

4.18 Ratio

 

 

Sorry, but I was checking your reply on my phone and only saw the first paragraph. Didn't know the DI can be exhausted even though I see it on the color indicator.

 

Also, how do you do an annual disinfection? This is new to me, never heard of that so this is very useful. Never mind, I found a link you posted before on here.

 

Thanks.

[AZDesertRat]

Your parameters are all good. One thing you will find is colder water treats better than warmer water since it is more dense, less fluid, so in winter months as water cools down the RO TDS will be a little lower. In winter when my water temp is 56-58 degrees is when I see my best RO only TDS.

 

At this point I would invest in a new 0.5 or 1.0 micron sediment filter and matched carbon block and a new SilicaBuster or Super SilicaBuster DI cartridge. I prefer non color changing since the dyes in color changing resins actually add a very slight amount of TDS to the finished water. It also forces me to physically test my TDS with my handheld TDS meter so I pay attention to how my system is working. As for the disinfection Spectrapure has directions on their website or if you do a quick serach using my username and disinfection you will find many threads where I detail the process of disinfecting the system the systematically flushing each filter and DI as they are installed so each does not contaminate or foul anything downstream and everything stays cleaner and lasts longer.

 

Spectrapure has replacement kits with the sediment, carbon and DI as a package to save a few $$. I recently saw a thread they started on RC where they may start selling their products via Amazon and Amazon Prime which would save a bunch on shipping costs. I'm local in Phoenix so can pick up at their shop but shipping can get pretty high if not.

[gsgentry]

Spectrapure has replacement kits with the sediment, carbon and DI as a package to save a few $$. I recently saw a thread they started on RC where they may start selling their products via Amazon and Amazon Prime which would save a bunch on shipping costs. I'm local in Phoenix so can pick up at their shop but shipping can get pretty high if not.

 

Perfect! As always, thanks for your help.

 

I am looking at their site now and trying to determine which DI to buy. I see the Standard and Super DI. I assume the standard is just the SilicaBuster and the Super DI is the Super SilicaBuster, correct? Also, Both of those have an option... twist-top shell or regular canister looking one. Does it matter which one?

[AZDesertRat]

This is the kit I would go with myself.

http://spectrapure.com/FILTERS-MEMBRANES-RESIN/FILTER-REPLACEMENT-KITS/CSPDI-System-Cartridge-Replacement-Kit-SuperDI-High-Capacity

 

It has the better 0.5 micron near absolute sediment and carbon block filters and the Super SilicaBuster DI which should last about 30% longer than the twist off cap standard SilicaBuster DI and only $1 more on sale.

 

If you want to stick with the standard 1 micron filters it saves you $9 but I think the upgrade to 0.5 micron versions is a good investment in protecting the RO membrane and extending its life.

[gsgentry]

Great! I think you recommended the 0.5 in a previous post you helped with with the I was originally looking at the machines.

 

As far as sanitizing, can I just remove the membrane and DI and do all chambers at once?

 

 

Thanks for all your help. I'm ordering now and will post results when I get everything in.

[AZDesertRat]

Yes you can. Make sure you don't use too much bleach though, more is not better.

[gsgentry]

OK... I will use 2-3 tablespoons and go ahead and do the entire system. Mine as well while I am at it and putting new filters in.

 

On a side note, putting a 3-Way valve in-between the membrane and DI and running it for a few before making water will help my DI last longer. Makes sense now.

 

But what I would like to know is can I do that to produce water for the pets, drinking, iron, coffee maker, etc.? I usually buy bottled water because our water is so hard and I dont want to gunk up stuff with the calcium build-up. Starting to think a valve make kill 2 birds with one stone.

 

Thanks for all the help!!

[AZDesertRat]

Absolutely!

The DI bypass serves many functions. You can waste the TDS creep, it gives you a place to draw a sample of RO only water to test with your TDS meter without having to disconnect any lines or remove the DI cartridge and it gives you a place to draw RO only water for drinking, pet watering and cooking. If you want to get a little more elaborate add a drinking water kit from www.purelyH2o.com like here:

http://www.purelyh2o.com/index.php?option=com_virtuemart&view=productdetails&virtuemart_product_id=93&virtuemart_category_id=78&Itemid=835〈=en

 

and your RO/DI now becomes a dual purpose system. The only additional thing you need is a check valve placed in the drinking water line so the pressurized RO does not get back to the DI filter. This diagram shows a drinking water kit installed on a reef RO/DI with the check valve in place. I had my personal system configured like this for over 10 years before getting my present system.

http://spectrapure.com/huds/4-STAGE-DWK-RODI-NAG.pdf

Love the RO water hooked to the icemaker and fridge faucet, tastes good and makes clear ice cubes!