slow sand filter update

The oldest filter here was started in 2007. Its still running. The sand has not been changed since it was started, and it has not been wet harrowed for 9 years. The output water needs to be tested, but the water is clear and looks clean. Still it must be tested. The other filters here are still running and in service. The three pond filters, and four other roof water filters are still running, and producing clear water. All need to be tested again. None have had the sand changed. Three of them have been wet harrowed twice in 5 years, but the sand has not been changed. As I get more time there will be updates. Other concerns have temporarily altered my focus. Now, I hope to get back to more filter work.

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2 Responses to slow sand filter update

  1. Sam Schmitt says:

    Dear filter_guy,
    I have just started with with slow sand filters in rural communities in Ecuador. Your blog has been incredibly helpful to me, thank you. I was hoping you could save me a lot of time and answer a couple questions: so far I am sifting sand with stainless steel mesh between the sizes of 0.425mm and 0.25mm, this is the sand I am using for the filters. However it is an incredibly long and slow process. What would be the effects if I simply installed roughly sifted sand (with a 0.6mm mesh) and then air scoured and backwashed (I know, not a process normally done with slow sand filters) just to remove the dust and smaller sand particles. The air scour and backwash *should* layer the sand (larger on bottom, smaller on top) and I could then remove the smaller sand on top and commission the filter. Would this work? It would save me countless hours of sifting.
    Secondly, what do you suggest for very turbid water sources? When it rains here the water becomes muddy.
    Thank you again

  2. filter_guy says:

    we are working on the website now. We will answer as soon as possible.

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