The question weather not you can safely have rocks in the bottom of the pond. The answer is yes but not in the ways they are commonly put in unless you want a lot of work. My koi pond has about 10 inches of rock in the bottom and has never been cleaned in 15 years. There is 11,000 lbs of 3/4 inch gravel on the bottom. It has never been disturbed from the day I put it in. The rock stays as clean as the day it was installed. You are thinking either I am lying or something is going on. You see I have a series of pipes running at the bottom of the gravel bed that are 12 inches apart and lots of holes in pipes and I suck water thru these pipes. During the winter about 3000 gph and during the summer about 9000 gph. The only maintenance that has been done on this pond since last Nov has been to feed the fish three times a week The pump baskets on the skimmer pumps will need to be cleaned out in the next month but that is it. I also built a pond for a client three years ago that wanted koi and rock on the bottom. So we installed bottom drains that were level with the 4 to 5 inch rock that we lined the bottom. The rocks were mortared together to keep debri out and let the bottom drains work. The bottom for the most part stays clean and has not needed to be cleaned. But these are not the normal ways that rock on the bottom is installed. Ponds with rock on the bottom the water will test just fine unless you are testing for HS or CO2. Since most people don't test for these they don't know they have a problem. Mike

Waterbug guy, First I will talk a little bit about concrete in water. You say it is a myth that concrete in water can kill fish and raise the PH. When concrete first sets up the surface PH is 12.0. Which is the same PH as a drain cleaner called "draino". As it is exposed to the CO2 in the air the PH goes down. But water is a very good leaching agent and so water will continue to try and get the chemicals out of the concrete. So will the PH in the water be raised? If the water has normal PH of 6.5 to 8.5 the answer is yes. The real question should be "how much will it raise it"? That question isn't easily answered as there are a lot of variables. Just to list some the age of the concrete, the condition of the concrete, is the water flowing over the concrete, the natural PH of the water, is the water being changed, and the volume of the water versus the contact area of the concrete. In some cases the rise might be so low as to make it very difficult to measure. But in other cases it can and does raise the PH to 9 to 9.5. At these levels it can and does kill fish. If I remember correctly you have stated that you are a pond contractor. If you are I hope you having started using roofing liner in the ponds that you build. Most of the time a person on this forum is never going to have a problem with roofing liner. Can there be a problem with roofing liner? This should be the question. The answer is yes. The chances that there could be a problem is very low. The largest pond product manufacturer in the US sent out a letter to all their customers a number of years ago. This letter said that all their liner in the future would be tested to be fish safe as they got a batch in that was not. In other words they were selling roofing liner as pond liner. This company had been selling a lot of liner for 10 years before this problem. If it had happen today with the wide use of the internet I would have think that some lawyer would have gotten this information and started a class action lawsuit against them and they would be out of business. The lawyer could easily have sued them not only for the cost of the liner that they had sold but for the cost to replace all those liners in the ponds built with them going back to the first time they sold this liner. The largest liner manufacturer in this country has told me that almost never would you ever have a problem with roofing liner but you might. I think that as a contractor you can't take that chance. If you were unlucky and did have a problem and were sued over that problem the lawyer handling the case would find out that they would sue for every customer that you have that has this liner. In other words you would be out of business. So is roofing liner toxic? No most of the time. But there is a small chance that there maybe a problem. I have only talked about 2 of the 8 things that you listed. I could easily talk about many of the other things listed but my point is this. You listed these things as black and white but they are not black and white. The only thing that is black and white about ponds is that all aquatic life will die. Mike

Before you bother to read this long-winded thingy please understand that I toss in barley straw in the head end of my pond not because I particularly believe it will help but - for me - its very cheap and canÂt really do any harm. But I donÂt use any of the so-called barley straw extracts...as to why, well, youÂve got to read the rest of this mess. I guess I have a different take on all of this starting with the difference between a "hypothesis" and a "theory". There are several hypothesis out there as to what barley straw does for removing or suppressing algae growth. The link IÂve provide below sums up a lot of what is believed to be known about how barley straw works...but this is all in the "hypothesis" stage. As best I am able to determine there are no peer-reviewed journal publications where someone has actually measured the hydrogen peroxide supposedly generated by the barley straw and in a situation which constitutes a decent experimental design; such an experiment should contain multiple ponds half of which receive barley straw treatment and the other half not along with in situ measurements for turbidity/chlorophyl or other quantitative measures of algae and measurements for those "things" that are believed to be contributed by the straw for suppression of the algae. Furthermore, if it was in fact hydrogen peroxide being produced from the straw then the continuous addition of small amounts of hydrogen peroxide from a dosing or metering pump should be capable of performing the same process but does not appear to do so. Also, there are some very sensitive assays for measuring hydrogen peroxide at the cellular level and yet I have not seen where anyone has actually measured hydrogen peroxide production. Many companies used to advertise barley straw as an algicide or algistat but no longer do so. Why? To quote Dr. LembiÂs write-up (see link below): "...The EPA defines a pesticide as "any substance or mixture of substances intended for preventing, destroying, repelling, or mitigating any pest." If a claim is made that barley "controls" algae (a pest), it is legally considered to be a pesticide. However, no company has ever registered barley for use as a pesticide. It has not gone through the testing required for registration. Therefore, barley cannot be sold as a pesticide to control algae. This ruling has serious implications for certified commercial applicators (individuals who have been state certified to apply aquatic pesticides for hire) and lake management specialists. These individuals cannot recommend or apply barley for algae control; this application would be the same as distributing an unregistered pesticide. Likewise, garden shops and nurseries cannot legally sell barley straw for the stated or implied purpose of algae control. Registration is required for all pesticides before they are sold or distributed, regardless of whether most applications go into larger bodies of water or into water gardens, even though the latter usually are privately owned, very small, and not likely to have an impact on the natural environment. A homeowner with a "private" pond or lake is in a different situation. For the homeowner who does work on their own pond, barley qualifies as a "home remedy" and does not come under EPA authority. ..." The key being that insufficient testing exists to register barley straw according to EPA. So now back to the main point of this thread: using a product that is derived from barley straw. If it is not known what the active agent(s) is/are in barley straw then how can one be sure that the "extract" really contains the active agents? What tests have they performed? IÂm obviously discounting the typical product endorsements that come without adequate data. IÂd go ahead and add it if I thought it would help. But maybe you might be just as well off taking some dollar bills, carefully shredding them and putting them in the pond instead. At least you could cut back on shipping and handling costs! LOL! As I have mentioned to some folks in other conversations there is a strong "placebo effect" here: having paid money for something, been told by the seller that it will work we really, really want to believe that itÂs doing itÂs job. But maybe not. So I say go for it if you will feel better having bought the product and if you want to believe. However, the hard data doesnÂt seem to currently exist to support the various hypotheses surrounding barley straw and barley straw extracts. Excuse me, IÂve got to go add a bit more barley straw to my waterfalls! ÂDavid

vieja, depends on what kind of frog tadpoles they are, as they all change at different rates. Leopard frog tadpoles can change into frogs a few weeks. Others such as Green frogs or Bullfrogs can take two years or more to change over. It all depends on the pond conditions, temperature and food availability. Since you describe them being "the size of a big marble", it makes me think you may have either Green frog or Bullfrog tadpoles. I have thought in the passed, that the Green frog tadpoles, I put into in my ponds had either died or had been eaten,since there was never a sign of them, only to find the next year some young frogs in and around my ponds. They are very good at surviving and staying out of harms way. "Horton"