How to build a small watertight pool?

After the grass-roots surface is drenched with water, it shall be plastered with plain ash twice (water cement ratio is 0.5). Wipe 1mm thick first, scrape hard with an iron trowel for 4 times, and scrape evenly, so that the plain ash fills the pores at the grass-roots level and is firmly combined with the grass-roots, and then wipe 1mm thick for leveling, so as to ensure the uniform thickness of the plain ash, and the sound of the trowel touching the grass-roots level cannot be heard.

Before the initial setting of plain ash, dip it in water with a brush, and evenly brush it horizontally to form hair, plug and fill the capillary channel, and increase the impermeability. The second layer is plastered with cement mortar (cement mortar is 1: 2.5, water cement ratio is 0.4) with a thickness of 5 mm.. During the initial setting of the plain lime layer, the cement mortar layer should be lightly plastered to avoid damaging the plain lime layer.

However, the sand in the cement mortar layer should also be pressed into the plain lime layer to a depth of about 1/4 of the thickness of the plain lime layer, so that the two layers can be firmly bonded together. Before the initial setting of cement mortar, gently sweep the mortar surface in one direction in sequence with a broom, without adding water or sweeping back and forth. In actual construction, the horizontal stripes are more firmly bonded than the vertical and oblique stripes, and the construction is more convenient.

Extended data:

Ponds are smaller bodies of water than lakes. The method of defining ponds and lakes is controversial. Generally speaking, the pond is too small for the boat to cross. Another definition is that people can cross safely without being completely submerged, or the water is shallow and the sun can shine on the bottom of the pond. The word pond may also be used only for artificial ponds.

In any case, there is usually no water inlet on the ground in the pond. Both rely on natural groundwater and rainwater or artificially introduce water into the pool.

Because of this, the closed ecosystem of ponds is different from that of lakes. The water in the pond is often green because there are many algae in it.