That wouldn't be a problem with AC. First the charcoal is not harmful to bacteria or anything else that is alive in the water. In fact bacteria will sometimes use the surface of the AC as a colonizing location as it does any surface in the pond. The AC does not release toxins into the water. It does not affect algae or particulates. It functions by attracting and trapping gas molecules on it's surface in a chemical reaction called adsorption. Once it has been completely covered by those molecules it stops working and must be refreshed or replaced. You should figure out where the discoloration in the water is coming from. Stains, discoloration and odors come from the breakdown of organic materials and the release of tannic acid or tannin into the water. Sources can be mulm, fish poo, excess food, dead plant material especially oak leaves and acorns and peat moss among other things. Pebbles on the bottom trap these and make the problem worse as the debris rots. Potting soil is a prime culprit. Do not use standard potting soil for pond plants. Free floating debris in the water is a particulate. It can also produce brown water. It is controlled through an efficient mechanical filtration system.It can be any of the things that cause stains in the water or other things entirely. AC does not control particulates. Mechanical filtration does not control stains and odors. All the AC you could add would not clear the water if you have material in the water that is actively rotting. To determine if you have stains, particulates or both fill a glass container with pond water and allow it to sit undisturbed for a couple of hours. Stain will remain diffused throughout the water, particulates will float or sink.

Yes, your tree is definitely dying (or might be completely dead at this point). It would have been better to allow your fig tree to remain dormant over the winter rather than try to keep it active and growing indoors. Here is what I would do now: Starting from the top of the tree prune all branches that are black. Continue working down the tree pruning all of the branches until you reach an area where the branches are still alive. You can tell if the branch is still alive by scratching the surface skin/bark with a fingernail.....if it is green beneath the scratch...that branch is still alive. Continue to remove all branches that are black/dead (i.e. all of those branches which do not have any green layer under the bark/skin layer). Even if all of the branches above the soil line appear dead and have to be removed, do not give up hope. It is still possible that a portion of the roots are still alive. After removing all of the dead branches, water your tree well. Take it "outdoors" ASAP and place it in a sunny area on the southern side of your house. Keep it close to a wall if possible. If any portion of your tree is still alive, it likely will send up shoots within a few weeks. Best of luck to you........

Jim, yes, we are in CT are blessed with mostly acidic soils and therefore our hydrangeas will be on a blue side. By adding lime you may temporarily change pH of the soil, but you have to do it for at least two season to make them bloom pink and you'll have to keep ammending planting area forever to keep it that way. Since you are talking about black-stemmed hydrangeas (Nigra?) you may not like the end result (I don't), but intermediate purple stage when it will transition from blue to pink is something that would make everyone ah! and oh! BTW, you could still continue your process in a winter. Just throw ashes from the fireplace under the shrub and they'll be absorbed by the soil during our wet winters. Good luck.

Hi jean There not all in 3ft square containers - only my apricot tree is in that size. I suspect it's a watering issue too. I think too much...recently. I'd like to know if it will spread to other plants, if I can stop it somehow, if I need to remove the damaged leaves which in fact I've done before only to have it come back again. This particular tree (I have no idea as to what it is...and when the officer from the parks dept came to check for beetles, he said he thought it was a laurel but wasn't sure) is about 8 ft tall counting the 18" high barrel it's in...which has a 29" diameter. It dries out quickly so I know it needs to be transplanted. It's been in this container for about a year. It grew wild on my roof a couple of years ago and I put it in this barrel last season. It needs to be transplanted, but if it's going to be problematic, I might get rid of it instead. Should I post a picture of the whole tree?