I apologize for the length of this post in advance. As has been mentioned above your high pH is most likely the result of the algae bloom that you are experiencing. Typically -again, as inferred above - algae consume carbon dioxide during the day causing the pH to increase and produce carbon dioxide (along with the bacteria and other things in your pond) during the night lowering the pH in some cases as much as 1.5 pH units (a factor of over 30x the hydrogen ion concentration!). Where I live we have to shut down the biofilters during the winter and essentially start the pond and filter up each spring. When this begins I will typically get a bit of suspended algae then a fair amount of stringy, slimy algae. Yet when I turn on the pumps (I usually wait until the water temp is above 45 or so since the biofilter and associated nitrifiers wont do much of anything below that temperature) the floating, stringy algae as well as the suspended algae are essentially gone within 72 hours. Even the algae on many of the rocks is either absent or drastically reduced. I try to use and do things that fall under the category of "do no harm". I have barley straw in the waterfall housing - not that I particularly believe that barley straw works just that at moderate application rates it doesnt appear to harm anything. Click here for article about barley straw I add salt to get the salinity level (not the same as measuring the sodium concentration) up to about 0.05%-0.1%. I do this because there are some non-scientific reports indicating that salt will suppress string algae growth. More importantly I do this to increase slime coat production of the fish until their immune systems can catch up with the other "bugs" in the pond - typically above about 55 degrees or so. If necessary I will add hydrogen peroxide to the tune of 1-2 pints per 1000 gallons (some folks add hydrogen peroxide at the rate of 1-2 pints per 100 gallons - using 3% store stuff). Both salt and hydrogen peroxide are, again, fairly benign in that all of the plants, frogs, toads, fish, etc. tolerate relatively wide variations in dose regardless of temperature and other factors. So if you dont know the exact pond volume or you happen to spill a bit too much...not a problem. Again, this fits in with "do no harm". Click here for Excel spreadsheet to calculate hydrogen peroxide doses -see bottom tab on spreadsheet In addition to all of this I will sometimes add daphnia once the water temperature hits 65 or above. These are highly efficient algae eating bugs, fish eat them, some fish fanciers actually grow them to feed them to their fish. The following is a web article, non-scientific publication on daphnia for algae control. Click here for web article on use of daphnia for algae control The other thing I do is add sodium bicarbonate to provide alkalinity and protect the pond from the potential of a pH crash. And it is at this point I wanted to clarify what alkalinity is and is not doing for you. You may just wish to skip what follows. If not, then you may want to open the jpeg graph/image in another window. If, after this, you wish more information please drop me an e-mail and I can explain the chemistry in much more detail or alternatively send me your phone number (if you are in North America!) and Im willing to call and chat with you, if you would like. Please dont ask me to call you just so you can give me a hard time I have others who are willing to do that for you! :-)) Alkalinity in our ponds is predominately the result of the bicarbonate ion. There are many other potential buffering systems out there but this is the only one of any significance in a natural system. The red line in the diagram represents what happens as you add your KH solution to your vial you start at some beginning pH (in this diagram Ive started at ~8.3 where the blue line passes through the red line) and as you add drop by drop the pH in the vial changes until you get a color change. This occurs at a pH of approximately 4.5. You calculate your alkalinity by counting the drops and then multiplying by 17.9 (the conversion factor to convert to ppm). Essentially what you have done is measured the amount of acid added to the vial - the horizontal distance from the vertical, blue line to where the pH changes to 4.5. So what? Notice that there are regions in the curve, where if you could record the actual pH as you added the drops, that the pH doesnt change too much - indicated by those ovals around pH 6.3 and 10.3. These are the points of maximum buffering intensity. Also notice that the pH drops fairly dramatically in the pH ranges of 8.3 (very important!) as well as around 4.5. These steep, vertical regions are ranges where there is minimal buffering of pH swings. In the pond described above the pH is as high as 9.5 (just visually move the blue line to the left a bit). When you add sodium bicarbonate it will not drop the pH much, but more importantly it cannot protect your pond very well from pH swings in the pH 7.7 to 8.7 region. Adding sodium bicarbonate will move the whole red line to the right (adds alkalinity) but you will still have this same region permitting pH swings to occur. Please do not think that I am saying not to add sodium bicarb (good, old Arm & Hammer). But to really control the pH swings you need to go after the algae. You need alkalinity in your pond to eliminate or protect against a pH crash. Again I apologize for this long post. Hope it is of some help. David

I have tried both the liquid and the powder bacteria and for me the liquid seems to work faster, I really like Ecofix I can usually see a difference in just a couple of hours.

hi mickys. not an "expert" and not familiar with green genies but does it not have an overflow fitted to return to pond in the event of blocking? a simple "T" return fitted would prevent a reocurrance. ie failsafe. its a green genie 2000 you said? if the ponds in full sun that should be halved, if you have a fairly heavy stocking level (plants and fish, frogs etc) halved again leaving the filter capable of maintaining 500 gals. (if the manfacturers claims are realistic). the pump is supposed to be able to recycle the volume of the pond in 1-2 hrs if the present one can do this i wouldnt upgrade as i think the extra dwell time in the filter may be benificial. how big is the pond? hope this is of help o/

Several new thoughts. If the 'old world pump' disturbs things, then turn it off. It looks nice anyway. Since things looked nice for a good while, I imagine that getting rid of the accumulated crud would solve your issue for a period of time. So, after the frogs are gone, pump the water down most of the way. You could even pump it to a cheap kiddy pool to let it settle out and decant it back in. Then, use a shop vac to suck crud off the bottom. I assume that butterfly was suggesting that you rebuild your rock mound into a micro stream. I assume that you have a liner under those rocks. You might need a slightly larger liner anyway. You would replace the rock pile with a lined sloped trench into the pond and cover the sides with some rocks and other natural stuff. Most importantly, you would put a bunch of plants into the stream. The roots would be your fine particulate filter. If I were doing it (I really like streams) I would start the stream back in those trees or bushes, to give it more length and make it appear more natural, flowing out from the woods rather than popping up from an unnatural mound.