Are they actually black (possibly black algae)? How large? Are they expanding? Are they rust spots? Frequently metal shavings from the mixer used on the plaster. Also other possibilities such as metals from the water supply source. A local professional, hopefully from the company that built your pool, should be able to analyze this. Tough to diagnose without visual input.
Negative terminal is grounded to the vehicle. Because the system is a negative ground system. Electricity will not flow unless it has a path to ground.
what is barter system
Harappa government is just like the caste system in India. It puts its lower citizens to the bottom of the food chain.
In a negative grounding system, current travels from positive to negative. In dc automotive power, the automobile chassis is utilized as a current return network for the negative to have a return path to the battery. It's much cheaper to produce a car with a negative ground system; because in a positive ground system, current flow is mastered with a switch that is wired in series through the automobiles positive power circuit instead of the negative power circuit such a case as switching on a dome light. The drawback to a negative ground system is that when a switch closes to complete a circuit (dome light coming on), the switch , at the exact moment of contact, incurs a slight spark, as current travels in a DC circuit from positive to negative. It's Basically a matter of production choice.#2There is no strict answer as to 'why' American cars are ground based systems. Rumors are that it was because of Benjamin Franklin's guess to the 'poles' of electricity as to which way current actually flowed, and degenerate into derogatory comments about American's ignoring the laws of physics. The convention for labeling batteries, despite physics, remains however.Despite any claim to the contrary DC Current ALWAYStravels from the ground (-) side of a battery to the positive (+) side; because electricity is made up of free electrons that accumulate on that side of the plate as a result of a chemical reaction.Also, all switches (except immersed switches - no arc switches used for explosive gas environments) will 'arc' when the contact is almost made.Also, production prices between positive and negative chassis systems are no different as electrical systems are the same in concept as well as production. There is no "requirement" that one system have a master switch (or any switch for that matter) because of its ground source. It is true however that most of these positive systems use better wiring, and relays for current load where American cars rely on the switch itself to handle the current load; which increases the cost and complexity of the system (Lucas prince of darkness, Jaguar comes to mind).Lastly, Ground based chassis systems have one inherent problem not normally seen on a Positive chassis system; known as a ground loop. A "ground Loop" is properly stated as an electron potential imbalance; where there are more electron's available in one point of the car as opposed to another point in the car / this is eliminated in positive based systems and compensated for in negative systems by running ground straps through the chassis.
It is the installation of ground rods at a service entrance distribution to bring the relative resistance to ground to be within 5 ohms of the utility's distribution network. This grounding system is then connected to the service distribution with a calculated size wire and connected to the distribution at a point within the distribution panel, where the service neutral wire joins the neutral bus bar.
Concrete/Gunite with plaster finish. Durability and ability to stand up to the winters. Replacing vinyl liners is a pain, and the appearance isn't as nice as the plaster. You'll only get about 5/6 months a year out of the pool. Don't have a spa included in the build of the pool. Develop a plan so that the spa is integrated, but on its own system, so you can use it year round. Good luck.
A gunite pool shell IS waterproof before plastering. First, gunite/shotcrete is not water proof. The reason for the plaster is to make the pool water proof. You don't have to and should not water proof gunite because it will affect the bonding properties for the plaster. Contrary to the previous answer, Gunite is in fact "waterProof" when correctly applied. Unless there are improperly prep'd cold-joints (the point at which one application has stopped for some reason -perhaps rain, slow truck turnaround, etc- and begun at a later time), a Gunite pool could virtually be "painted", providing a high steel-trowel finish was applied to the Gunite. But, Gunite pops (begins to set and cure) faster than typically appied Marblite or Diamond Bright type cementitious finishes. Actually, the Gunite "finish" surface is purposely left fairly rouch, providing a better surface to which the finish/color material may bond.
arrangement, way, system, footing, foundation, support, base, ground, footing, bottom, groundwork
In North America on a 120/240 volt home electrical system, the ground pin on a duplex wall receptacle is on the bottom.
This is when a building is separated from the ground that it is built on by large plates. One plate is secured to the ground and the other is secured to the bottom of the building. These plates move a certain distance when the ground shakes.
its the bottom of your digestive system. ;)
The system is negative ground.
it has a negative ground system.
Depends on what you're looking for. A plaster pool can be drained and painted but it does crack and certain chemicals can aid in the cracking process. A gunite pool would be a better but probably a more expensive choice than plaster. The liners are great. My brothers pool is an inground pool with a liner that was installed in 1983, in a flood and hurricane zone. It has never torn, wrinkled, or lifted up in any way. In a major flood zone such as we have here in south Louisiana, a plaster pool can lift up and begin to float. The liner is also very smooth and comforting to the feet when playing in the pool. My liner was installed only 5 years ago and we have been very satisfied, although it requires a different set of chemicals. A lined pooled should never be drained completely. Either way you choose, I would suggest going with the saltwater filtration system. It turns out to be less expensive in the end. Hope this gives you some things to consider.
If it's not ground water (and I'm unclear how you would know that it isn't), it must be runoff from the steeply sloped grade running to the pool I assume. If that's the case; create a drainage swale around the perimeter of the area in question or install an underground perimeter drain system around the same area.
The top button is pointing to the right, the middle button is pointing to the ground and the bottom button is pointing towards the left. Hope this helped :)
Most all vehicles built today have a negative ground system, and have had for decades.