RODI pump not increasing pressure.

Ron Tischer

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I am at a loss with why my 8800 aquatech pump is not increasing the pressure. everything was fine untill I changed out my 2 RODI filters and 2 carbon filters. I did forget to flush the carbon filters so added a 3 way after the carbon filters to flush prior to getting to the RODI filters. After I changed out the filters, I turned everything on and the pump was not increasing the pressure. I thought maybe the pump was bad so I bought a new 8800 pump and installed it. still no change. I thought then maybe the pressure switch was bad so I went ahead and bypassed the pressure switch by plugging the power directly to the pump (I know not recommended but trying to troubleshoot).
flow = water source through a spigot to the pump then sediment and 2 carbon filters. Then to 2 rodi filters and finally 2 resin canisters. The gauge is the good glycerin filled one so I seriously doubt that is the issue especcialy since I am getting TDS of over 130 after the 2 RODI filters.

Any help would be greatly appreciated. Thank you very much

20250519_095822.jpg 20250519_095835.jpg 20250519_095917.jpg 20250519_095932.jpg
 

UncommonSense

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I have not. The pump does turn on and sounds like it is running.
But no appreciable increase in flow or pressure?

Assuming there definitely isn’t a leak; the only other things that come to mind are:

Less likely: your original booster pump wore out, and your replacement is defective…

More likely: you have a large chunk of debris clogging flow through the filtration system; likely in a tube!

Edit: this assumes the filtration system has a confirmed supply of pressurized water!
 

Shirak

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I am at a loss with why my 8800 aquatech pump is not increasing the pressure. everything was fine untill I changed out my 2 RODI filters and 2 carbon filters. I did forget to flush the carbon filters so added a 3 way after the carbon filters to flush prior to getting to the RODI filters. After I changed out the filters, I turned everything on and the pump was not increasing the pressure. I thought maybe the pump was bad so I bought a new 8800 pump and installed it. still no change. I thought then maybe the pressure switch was bad so I went ahead and bypassed the pressure switch by plugging the power directly to the pump (I know not recommended but trying to troubleshoot).
flow = water source through a spigot to the pump then sediment and 2 carbon filters. Then to 2 rodi filters and finally 2 resin canisters. The gauge is the good glycerin filled one so I seriously doubt that is the issue especcialy since I am getting TDS of over 130 after the 2 RODI filters.

Any help would be greatly appreciated. Thank you very much
I am confused by a couple statements. You changed the carbon blocks and you stated RODI filters. RO and DI are not the same thing. Did you change the RO membranes?

You also state TDS over 130 after the 2 RODI. Is that after the RO membranes? After DI?

If you are getting 130ppm tds after the RO filters than it sounds like a problem with the RO and tap water is bypassing the RO membrane in some fashion. If the water is doing this then you won't get pressure because the flow is too fast.

I also see you have one of those auto cut off valve things.. did you disconnect any water lines when changing filters and possibly mix something up putting back together?
 

UncommonSense

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If it turns out to be a simple plumbing mix-up; Save that spare booster pump if you can’t return it!

They do have a lifespan… — mine started spitting out small black chunks (likely bits of the pump itself) into the sediment filter recently, and has reduced in pressure from 95PSI to 75PSI… it’s due for replacement after many hard years of use!
 
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Ron Tischer

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I am confused by a couple statements. You changed the carbon blocks and you stated RODI filters. RO and DI are not the same thing. Did you change the RO membranes?

You also state TDS over 130 after the 2 RODI. Is that after the RO membranes? After DI?

If you are getting 130ppm tds after the RO filters than it sounds like a problem with the RO and tap water is bypassing the RO membrane in some fashion. If the water is doing this then you won't get pressure because the flow is too fast.

I also see you have one of those auto cut off valve things.. did you disconnect any water lines when changing filters and possibly mix something up putting back together?
Yes, I changed both the carbon filters and both the RODI membranes. TDS is over 130 after the 2 RODI membranes. The only thing I added was the 3-way valve after the carbon blocks so I could flush the carbon after replacing it before it goes to the RODI membranes. I was pretty careful I thought after removing the connections to the RODI membranes and putting back together as it was before. But I can double check. Is the water cut off valve you are talking about the white connection with the 2 input and 2 output lines going through it? I did not disconnect that.
 
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Ron Tischer

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If it turns out to be a simple plumbing mix-up; Save that spare booster pump if you can’t return it!

They do have a lifespan… — mine started spitting out small black chunks (likely bits of the pump itself) into the sediment filter recently, and has reduced in pressure from 95PSI to 75PSI… it’s due for replacement after many hard years of use!
Thanks. It never hurts to have a backup.
 

UncommonSense

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Yes, I changed both the carbon filters and both the RODI membranes. TDS is over 130 after the 2 RODI membranes. The only thing I added was the 3-way valve after the carbon blocks so I could flush the carbon after replacing it before it goes to the RODI membranes. I was pretty careful I thought after removing the connections to the RODI membranes and putting back together as it was before. But I can double check. Is the water cut off valve you are talking about the white connection with the 2 input and 2 output lines going through it? I did not disconnect that.
This sounds a lot like water leaking around the RO membrane(s), as @Shirak spotted!

It is technically possible for the RO membrane(s) to be misaligned in their housing(s) enough that water leaks around their seals!

If tightening the housings (I use a vise on the cap and both hands to tighten) does not reduce product water TDS; try opening the RO membrane housings up to confirm that you didn’t have a sealing gasket fall off of one RO membrane, or something silly like that!

Yes, the white square component with four push connectors is your automatic water shutoff; they usually fail open when they fail. It isn’t likely to be your issue, but should not be 100% ruled out.
 
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Ron Tischer

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This sounds a lot like water leaking around the RO membrane(s), as @Shirak spotted!

It is technically possible for the RO membrane(s) to be misaligned in their housing(s) enough that water leaks around their seals!

If tightening the housings (I use a vise on the cap and both hands to tighten) does not reduce product water TDS; try opening the RO membrane housings up to confirm that you didn’t have a sealing gasket fall off of one RO membrane, or something silly like that!

Yes, the white square component with four push connectors is your automatic water shutoff; they usually fail open when they fail. It isn’t likely to be your issue, but should not be 100% ruled out.
Thank you. I will take a look at that.
 

Shirak

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Yes, I changed both the carbon filters and both the RODI membranes. TDS is over 130 after the 2 RODI membranes. The only thing I added was the 3-way valve after the carbon blocks so I could flush the carbon after replacing it before it goes to the RODI membranes. I was pretty careful I thought after removing the connections to the RODI membranes and putting back together as it was before. But I can double check. Is the water cut off valve you are talking about the white connection with the 2 input and 2 output lines going through it? I did not disconnect that.
Picture which shows the RO out and Waste out on the RO canisters looks correct for the tubing connections. If you are getting really high TDS on the RO output then it's likely a leak inside one or both of the RO housings. Really important that the small pipe with the o-rings on the RO membrane is inserted first and is fully seated seated into the housing. Check the large gasket is on the input side with the gasket seated all the way around the inside of the RO housing and isn't folded over.

I would suggest disconnecting the RO line where it enters the DI canisters for now. If you run 120tds water into the DI it will use up your resin fast.
 
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Ron Tischer

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I want to do a courtesy reply to everyone that shared their thoughts. I put the old RODI membranes back in to see if that made a difference. Sure, enough the pressure came up and I am getting 1 TDS after the membranes and 0 after the resin. Thank you to everyone that took time out of their day to be of assistance. It is greatly appreciated, and you helped this reefer a ton!! Now to figure out why the new ones didn't work....
 

UncommonSense

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I’m glad you found a solution to keep the system up and running!

Assuming the new ones are direct replacement membranes, the likely culprits are:

- Install error
- Missing/damaged sealing o-rings/gaskets on one or both membrane(s)
- factory installed shipping plugs on membrane(s) (less likely/common)

I’m glad we could help! — feel free to ask if you have any more questions!
 

Buckeye Hydro

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Feel free to give us a call when you are in front of your system and we can get it sorted out.
 

Tangdora

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Had a similar issue but will note I’m on well with fluctuating psi. First just open the pump to make sure all the diaphragms are in tack and seated correctly. However will say all my problems went away with my 8800 when I upgraded the inlet side only hose from 1/4 to the 3/8 size and adapter that comes with the pump.
 

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