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Blagdon V8 Pondseal

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1 Review

Brand: Blagdon / Type: Pond Chemicals

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      19.09.2008 13:19
      Very helpful



      A solution to the problem of ponds with porous concrete bases

      When we bought our house around 12 years ago, one of the many attractions that made up our minds for us was the fish pond in the back garden. Even though it had not been well looked after by the previous owners, the thought of tinkling water, beautiful water plants and colourful fish just added something to the admittedly otherwise small space.

      However, the trickle of water was at that time just an ambition. The pond itself had no waterfall nor even any fish. The first improvement was therefore to create the waterfall. I found a suitable pump and filter from the Hozelock range and designed how the waterfall would work. I wanted a double fall waterfall and this arrangement would fit nicely with the amount of space available behind the pond basin.

      I constructed the waterfall solidly out of reinforced concrete and rockery stones and it certainly looked just as I had hoped. Giving the concrete plenty of time to set, the time finally came to try it out. The results were superb, exactly as we had hoped. However, after running the waterfall for a while I noticed that the water in the pond seemed to be "disappearing". I realised that evaporation is greater when a waterfall is run than in a still pond but even so the amount being lost seemed excessive. The trouble is, I couldn't work out where the water was going.

      I must admit I didn't do anything about the problem immediately. When water disappeared I refilled the pond from the rainwater butts. Mostly I limited the time when the waterfall was running to just those occasions when we were in the garden. Water didn't seem to disappear then so that did seem to confirm that the problem was the waterfall and not the pond.

      Behind the pond was at that time a very large cherry laurel and this really did dominate the corner of the garden. I wanted to remove it but put it off for several years until finally I'd had enough; it had to go. I soon began to regret it. I discovered, once the majority of the laurel had been removed, that beneath it someone had used the garden as a rubbish tip. I uncovered a broken up chest of drawers, broken bits of iron fencing and sheets of corrugated iron.

      The latter, I suspect, was part of the construction of the pond. However, there were far more sheets than were needed to form a container in which to form the concrete base for the pond. Unfortunately some of them were under the waterfall extension and couldn't just be partially removed or even left in place if we ever wanted anything new to grow there.

      Some time after completing the work I noticed that the water in the pond was far lower than normal. Closer inspection revealed a crack across the back of the pond, just below where the waterfall was joined on. It seems that, despite packing earth and rocks back under the waterfall, it's weight, hanging off of the back of the pond, had caused it to subside a fraction, just enough to crack the base.

      Clearly more substantial repairs were required to I decided to take the opportunity to also address the problem of the leak in the waterfall. Once I'd cleaned out the entire pond and filled the crack I decided that this time I would seal the entire pond and the waterfall before refilling it. I though about various waterproofers such as Thompsons but these are specifically NOT recommended for ponds, where the fish may be affected. I asked the advice of the local water centre and they recommended Blagdons V8 Pond Sealer. It is expensive, around £30 for a 2.5 ltr tin, but it goes a long way.

      V8 looks a bit like a thick clear lacquer. You apply it with a brush which, the tin says, can be cleaned with cellulose thinners. I used thinners to keep the brush soft between usages but, to be honest, they didn't fully clean the brush once I had completed the job and so I would suggest that you resign yourself to throwing it away.

      The concrete doesn't have to be bone dry before you apply the V8. Apparently a little humidity helps cure the coating. You do have to leave it some time between coats but not more than three days. I applied three coats to the entire base and waterfall, over a period of a week or so. The finish is a little shiny, as would be expected, but once the water is in you don't really notice any difference. I left the final coat about five days before refilling the pond.

      The pond is now back in use and the waterfall runs full-time. I still lose some water but no more than would be expected through natural evaporation. Blagdons V8 seems to had done a really good job. I still have about a quarter of the tin left in case I ever need to do any more repairs.

      If you have a similar problem with your pond then I would recommend Blagdons V8 to solve it.


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    • Product Details

      Suitable for applying to concrete in and around ponds.

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