Dittohead, thanks the overview - I've been reading back threads, and the experience you have and the help you give here is really valuable.
After posting my stuff, I saw on an older thread that you were shooting for a backwash rate for Katalox Light of around 15 gpm/sf. It would have been interesting to see if a higher BW would have affected things for me. My well pump could handle it, but as mentioned, the crazy high pH and high hardness were doing a number on my wife's hair, and that had to stop
The KL literature calls for 10-12 gpm/sf, presumably 10 for cold water (which my water is) and 12 for warm. For my 13" tank, 10 gpm equates to 11 gpm/sf with zero adjustment (worst case), and 15.5 using the Vortech claim of 30% (best case). Per Reach4's chart, this results in somewhere between 30-40% bed expansion. So my 10 gpm backwash seems to be "by the book", and if the Vortech claim is valid, hits your higher target.
My pH and hardness levels were coming down, but slowly. Between the first and second test, I ran the equivalent of 2-3 month's worth of backwashes. A higher BW rate may have brought the levels down quicker, I assume by removing the hydrated lime binder, but it looks like at best it still would have taken a lot of time. While I could live with temporarily high hardness, the pH in particular was proving stubbornly high. I wish I could have tried the higher BW to get the data, but as mentioned, I want to stay married
I spoke recently with a designer/dealer, and while KL works fine for most of their customers, they have apparently been seeing cases like mine, enough so that they are planning to include a disclaimer with their literature and recommendations. They are not sure whether certain water chemistry causes the pH/hardness spike, or whether some batches of KL have higher amounts of the hydrated lime binder. I'm not sure if they have tried higher backwash rates.
I was disappointed in Watch-Water’s customer service. After several days in touch with a US rep and some emails to Germany, I didn’t get any meaningful help or advice. They seemed baffled.
I understand that for many cases KL works well, but I think their literature should disclose about possible increases to hardness and pH. Their recommendation for inlet water pH is 5.8-10.5...it seems to me there should be some kind of warning about using KL when a customer is starting with high pH. Possibly they should raise their recommended backwash rate also (they did this once – I stumbled on an older spec sheet, and it used to be 8-10 versus the 10-12 current).
One of the nice things about the Birm literature is that its limitations and contra-indications are clearly disclosed, like not playing well with H2S
So now, I have mixed media of 1 cf of Birm, and 1 cf of Centaur carbon, and once again I should have researched more first! But for the time being, the water is delicious.
I mentioned above that I had spoken with a tech rep for Clack/Birm, and he said that with lower to normal pH, the H2S wouldn’t be terrible for Birm, but at higher pH like mine, it would cause the Birm to fail prematurely. I had hoped that with air injection to oxidize the H2S, and Centaur carbon higher in the tank to intercept the H2S, the H2S might leave the Birm unmolested.
Looking back, I probably should have gone with straight Centaur carbon, because other than the high pH, my water is pretty tame and unremarkable. Next re-bed that’s probably what I’ll do, and if I can remember, will post here how long the Birm/Centaur carbon lasts. Hopefully the two media and the hydrogen sulfide can play nicely together for a while
Thanks again for your time and interest, and all the great info you contribute here!