I can't imagine why they might be harmful, but I also have no idea why adding a Bestmin would cause more bubbles. The water coming out of the RO into the accumulator contains dissolved CO2 under slight pressure, and when that water flows out into an atmospheric pressure container you might expect small bubbles of CO2 adhering to the walls of the container as the dissolved CO2 becomes CO2 gas. But a Bestmin should, if anything, tend to decrease the amount of dissolved CO2 in the water, so I'm stumped as to what's going on here.

P.S.
We don't know exactly what is inside those Bestmin filters, but probably calcite (CaCO3), dolomite (MgCa(CO3)2) , perhaps some calcined dolomite or Corosex (CaO and/or MgO), all of which would be expected to increase hardness and bicarbonate, and reduce carbonic acid and CO2 when dissolved into water.

Yeah, it's very strange. What's even more perplexing and frustrating is that my GH and KH values have retured to that of my RO system. They are back to 1°D . I have no idea what is going on.

I've contacted BWT South Africa who say that my RO system is removing too many minerals for the Bestmin to mineralize the water beyond 1°d. From how it is advertised, Bestmin is to be used in conjunction with an RO system, so this makes no sense to me. He recommends replacing my RO with the bestaqua membrane or using bestmin as a standalone connected directly to main water supply (GH 5°d, KH 5°d).Definitely not paying for another filter that may not even achieve my desired water characteristics. Also, wouldn't bestmin just increase GH/KH of my tap water if connected to mains?

According to BWT, my other options are the bestMAX premium or the bestMAX SMART. If the bestmax premium is the same technology as the BWT penguin filter jugs, may tap water GH will be reduced from 5°d to 1°d and KH reduced from 5°d to 2°d.

Definitely regret going the bwt route. It just makes no sense to me how the Bestmin has stopped remineralising.

Update. Using the bestmin as a standalone with my mains, GH was decreased from 5°d to 3°d. However, KH was increased from 5°d to 11°d.

2nd update: waited an hour and retested. GH and KH are now 4°d

Liverbird_8 wrote:I've contacted BWT South Africa who say that my RO system is removing too many minerals for the Bestmin to mineralize the water beyond 1°d. From how it is advertised, Bestmin is to be used in conjunction with an RO system, so this makes no sense to me.

Makes no sense at all to me. The flow rate, and the dissolved CO2 and pH (those last two are related), have the most effect on how much mineral gets dissolved. Having low, even zero mineral should not decrease the amount of remineralization.

Liverbird_8 wrote:He recommends replacing my RO with the bestaqua membrane.

Perhaps he prefers you have an RO system that he's familiar with? I can't see much sense in this either.

Liverbird_8 wrote:or using bestmin as a standalone connected directly to main water supply (GH 5°d, KH 5°d).

That dosen't make a bit of sense. Your water is a little too hard, and Bestmin is designed to add hardness and alkalinity to water that is too soft.

Liverbird_8 wrote:According to BWT, my other options are the bestMAX premium or the bestMAX SMART.

The decision to ditch your RO and go with just a Bestmax for softening depends on why you initially chose to go with RO. Most people do that to get rid of nasty things like chloride, and if that's the case here you don't want to get rid of your RO system.

Liverbird_8 wrote:Definitely regret going the bwt route. It just makes no sense to me how the Bestmin has stopped remineralising.

They do seem to be a source of mystery and unpredictability. One advantage to using a simple calcite filter with perhaps a small amount of Corosex is that their contents are known, have been around for ages and are fairly well understood.

I would disregard most of what he said, he admitted that he was just a salesman and put me in touch with a technician who has more knowledge about water chemistry. Like Pat mentioned in another thread, the BWT technician said that water with lower pH will more easily dissolve minerals and yield higher GH and KH levels. In addition, he said that replacing my RO system with a BWT RO will not result in more mineral injection. I'm hoping I can return the bestmin cartridge but not optimistic that I'll get refunded.

You are correct in that my decision to use RO water was to avoid corrosive ions and inject only the minerals I need. As of yesterday I have been using 70/30 water but don't see it as a long term solution.

I have contacted South Africa's everpure distributor sponsored by the SCA south africa. They are coming on Monday to conduct water tests and recommend a system that will achieve specs similar to that of 70/30 water (from what I understand, these levels are nonscaling and non-corrosive while falling within the SCA taste recommendations).

As per your calcite recommendation, I initially intended to attach an Everpure 7CC calcite feeder in place or after the bestmin. However, I am not sure I will get what I want.

Sorry about the constant questions, although, you seem to be passionate about the subject. Hopefully, my experience can help others. Thanks again for your input!

Seriously considering a carboy solution as it might be the only way to get exactlywhat I want. Got some reading to do on how to plumb in using carboy. Thankfully there is a lot on this forum.

Following the advice of BWT, I have used T connectors to feed both RO water and Tap water (controlled with a ball valve) to the Bestmin cartridge. In theory, allowing more or less tap water to pass through valve will allow me to alter my GH and KH levels. The obvious downside is that I am introducing chloride ions into the water which almost defeats the purpose of RO + remineraliser. Would adding a basic carbon filter or chloride eliminator (if it exists) between mains and Bestmin be a good idea?

Will soon post an update on how my GH and KH values have changed.

Liverbird_8 wrote:Would adding a basic carbon filter or chloride eliminator (if it exists) between mains and Bestmin be a good idea?

The bestmin already contains activated carbon, so not much reason to add that. And a simple chloride eliminator does not exist*, that's why people go with RO to get rid of chloride.


* A mixed bed de-ionizing cartridge like the Claris Prime will reduce chloride, but that's expensive and by no means simple. A Zerowater pitcher filter is a common home de-ionizing filter that removes chloride (and everything else) that could be used instead of RO. But if you have high TDS water it's not cost effective, and is not an inline option.