Hi all,
I have kind of an interesting issue that I cannot figure out. Recently I measured 12 TDS coming out of my RO chamber with tap water of 140 TDS, and since the membrane was about 1.5 years old, I decided it was time to replace it given the higher rejection rate. Ordered the new membrane, installed it last night and was getting 14 TDS out of the RO chamber initially, and this actually increased to 20 TDS after about an hour. After about another hour, it dropped to 16 TDS but hasn't dropped below there and I cannot figure out what is wrong here. While after DI, it is coming out 0 TDS, it should at the very LEAST be no more than 12TDS after RO like the old filter was immediately before changing it, so I am not sure where the error is coming from.
Here's the stats as it currently stands:
BRS 75 GPD 4-stage system - https://www.bulkreefsupply.com/75gpd-4-stage-value-ro-di-system-bulk-reef-supply.html
Pre-filters are 1.5 months old, so I know they are good still
Tap - 140TDS
RO - 16 TDS (previously 12 with old filter immediately before changing)
RODI - 0 TDS
Things I do not know and wish I did:
1. Water pressure (but this shouldn't matter here - main issue is why am I getting higher TDS immediately after changing to a new filter?)
2. TDS of RO water when the original membrane was new back in late 2021 (I only knew about measuring final TDS after DI, which was always 0 so it is hard to compare to the RO TDS values I am getting today). Maybe the original membrane also took a while to drop in TDS and my DI was simply eating the excess without me knowing at this time - I'll never know this because I didn't measure :/
So there are a couple key things I do not know. Despite this, the way I see it is this: the TDS of the new membrane needs to be at equal to the old one to know it is working properly since no other variable changed - and in this case it clearly is not. I let the new membrane run about 2 hours with the DI disconnected to see if the TDS slowly creeps down, but I wasn't able to get it lower than 16. I tried removing the filter and re-seating it but everything looks okay inside visually. Could it be the filter just needs to run and re-hydrate for over 2 hours since it was dry? Maybe this filter is defective? I may try re-installing the old one and seeing if I still get 12TDS although just a day ago I know I was. I am running out of options!
Any input/anecdotes appreciated!
I have kind of an interesting issue that I cannot figure out. Recently I measured 12 TDS coming out of my RO chamber with tap water of 140 TDS, and since the membrane was about 1.5 years old, I decided it was time to replace it given the higher rejection rate. Ordered the new membrane, installed it last night and was getting 14 TDS out of the RO chamber initially, and this actually increased to 20 TDS after about an hour. After about another hour, it dropped to 16 TDS but hasn't dropped below there and I cannot figure out what is wrong here. While after DI, it is coming out 0 TDS, it should at the very LEAST be no more than 12TDS after RO like the old filter was immediately before changing it, so I am not sure where the error is coming from.
Here's the stats as it currently stands:
BRS 75 GPD 4-stage system - https://www.bulkreefsupply.com/75gpd-4-stage-value-ro-di-system-bulk-reef-supply.html
Pre-filters are 1.5 months old, so I know they are good still
Tap - 140TDS
RO - 16 TDS (previously 12 with old filter immediately before changing)
RODI - 0 TDS
Things I do not know and wish I did:
1. Water pressure (but this shouldn't matter here - main issue is why am I getting higher TDS immediately after changing to a new filter?)
2. TDS of RO water when the original membrane was new back in late 2021 (I only knew about measuring final TDS after DI, which was always 0 so it is hard to compare to the RO TDS values I am getting today). Maybe the original membrane also took a while to drop in TDS and my DI was simply eating the excess without me knowing at this time - I'll never know this because I didn't measure :/
So there are a couple key things I do not know. Despite this, the way I see it is this: the TDS of the new membrane needs to be at equal to the old one to know it is working properly since no other variable changed - and in this case it clearly is not. I let the new membrane run about 2 hours with the DI disconnected to see if the TDS slowly creeps down, but I wasn't able to get it lower than 16. I tried removing the filter and re-seating it but everything looks okay inside visually. Could it be the filter just needs to run and re-hydrate for over 2 hours since it was dry? Maybe this filter is defective? I may try re-installing the old one and seeing if I still get 12TDS although just a day ago I know I was. I am running out of options!
Any input/anecdotes appreciated!
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