Hi, Algae is frustrating isn't it? The stuff grows on the bottom of arctic ice and in 180 degree water coming out of hot springs. If you have a pond, algae happens. IMO battling algae with chemicals, uv rays, and (to some extent) mechanical filtration is a war you can't win in the long run. Once you stop the chemicals, or the uv filter, or the mechanical filter clogs up the battle is lost. My thoughts on reading your post are these: First, patience. Your pond is new and needs time to find balance. Right now bacteria is establishing itself on the liner, the rocks, and every surface it can. This beneficial bacteria will convert the biological waste through the nitrate cycle-but it needs time to establish. Once the algae has less to feed on, the bloom will subside. The purpose of the filter material in your waterfall filter and perhaps your skimmer is to give the bacteria more surface area to live on. 5,000 gallons going through a 22 inch waterfall filter probably means that the bacteria doesn't have time to convert the nitrates. Again, imo, I would divert half the water to an upflow biological filter and/or stream. 100 gallon per hour per inch of waterfall is plenty for a nice effect, that means yours needs about 2,200 gph. The rest of the water you could divert-gravel streams are beautiful and provide lots of surface area-stock tanks are ugly but do a great job if built as an upflow biological filter. Your equipment is fine. It's probably too late now to add a bottom drain and that is a pity. The ideal imo bottom drain and skimmer to settling tank, pump in tank to upflow biological filter, stream to waterfall, waterfall to veggie filter, weir to pond. Your fish load is probably fine right now too. 4 large koi in a 6500 gallon pond is not unreasonable. The baby's aren't contributing much to the bio-load of the pond right now. Find homes for most of them before they get much bigger. Oh, and don't over feed them. Algae happens. But thankfully so does balance. You can tip the scales in your favor by eliminating as much as the bio load as you can (skimmer for leaves-bottom drain for sinking mulm) increasing the surface area for aerobic bacteria, and keeping the bioload resonable for your pond size and filtration (mechanical, bio, and veggie. But mostly try to be patient. Depending on water and air temps, at about 3 weeks from new pond start up you will have a BAD algae bloom; at about 5 weeks you will notice the water getting a bit clearer, between weeks 6 and 8 you will notice it getting markedly better. Next year it will happen quicker as the bacteria establishs. Good Luck with your new pond! And patience! Here is a link that might be useful: Come Join Pond Chat!

margomnyc, sorry for the delay, I took a Houzz break after we finished. As far as the Neolith, we are really happy with it. We've had no chips thus far after 6+ of heavy use, and nothing has stained it. The satin finish is very nice -- not too shiny but it's not totally matte. I use glass cleaner to wipe it down as some other cleaners can leave streaks. Overall, I'd recommend it. oldbat2be, thank you, I'm glad to hear you like it! I could use a sous-chef and may take you up on that offer! ;)

Check out this house with shou sugi ban: I like the color of the deck and the railing they uses. There are more pictures on Houzz for ideas on landscaping as well. I like their use of rain chains. Do you have room for a lap pool?

It's gorgeous and love your pool inspo photos. The look reminds me of either MCM or Zen garden, both of which will fit your vision. And this 'wood' wll never fade. Does it come in a matte or flat finish to avoid glare off it?