Kellynch

I'm very grateful for the help. I see what you mean by the polytunnel effect. I think I will try and use the thick black plastic idea you mentioned 😊

Part of my garden has a weed membrane covered in small stones for decoration. The membrane does very little to stop weeds. I heard that a vinegar solution kills weeds, though there doesn't appear to be general agreement as to when you can pull the weeds after spraying. As it's now rainy season, would it be worthwhile to use the vinegar solution and then cover the weed area with clear plastic, so that the sun would still help, then pull the hopefully dead weeds after say a day or two?

Very thankful for your suggestions. I'll definitely check out the packet suggestions. Re tank types - they are the concrete ones. Re the levels in the tanks - I see what you mean. I looked back at my OP and didn't mention that water was seeping from out of the tank lid, especially when using the washing machine. From what is mentioned about the sludge build up along with the tanks being full, of liquid, I think I was on the right track with too much sludge, which is where, hopefully, the photo suggestions will help.

I have the tanks sunk into the ground for house waste eg sink and toilet. My understanding is that waste will breakdown naturally in the tanks and the 'cleared' water absorbed into the garden. Some locals tell me that there's no need to add anything extra eg powder or bio liquid. However, I'm thinking about one set of tanks that has a fair bit channeled into them - Kitchen sink, bathroom toilet and sink, utility sink and washing machine. We've had difficulty with these tanks being full. We got the tanks emptied but they fill up fairly quickly bearing in mind that there are just three people living in the house. A plumber is emptying the tanks and clearing out the pipes for any blockage eg fat and grease but all seems fine. I have other sets of tanks for bathrooms that are fine. I'm wondering if the waste volume for the problem tanks is not helping and perhaps the waste isn't breaking down quickly enough? Should I add some bio powder or other liquid to help it along? Here's a photo of powder that was recommended.