Article: Doing this takes quite a long time for the algae to bloom. See the next method for something faster.
Question: What is a summary of what this article is about?
Put aged aquarium water in a clear container. Expose the water to the sun.

Problem: Article: ) sounded together. If you speak of only two notes that are to be sounded then that is known as an interval (like a distance). in the photos using sticky notes on a keyboard below... but C shown as three notes on lines of sheet music would not show that concept. Notice the simpler of three-note chords are the major chords "C, F, and G" that are made up of only white keys spaced and shaped exactly the same way "every time." That shape (like a formula) uses fingers "5, 3, and 1". The other 3-note major chords use the same fingering but slightly differing shapes because of sharps and/or flats:  Find the fundamental note (C or F or G), and Go across the ivory keys to the 3rd note using the 3rd finger and And the ivory 5th note using the 5th finger (the thumb). So, the formula for those three chords is simply left to right on the left hand (numbered 5, 3, 1) starting at the fundamental basis note which names of each chord. Notice that "D chord" is exactly the same shape as "A chord" in the photos using sticky notes on a keyboard at the left... but D shown as three notes on lines of sheet music does not show that idea as clearly.  Examine the shapes of the hand for A and D chord and you'll agrees that they are almost the same as C, F, G -- but it has the middle fingered-note "sharped" ("Sharping" or "flatting" is really only a half step between notes.). So, these both have a black key for the middle finger -- left to right on the left hand (5, 3#, 1) where the "#" symbol means "sharp" which is most often the black key to the right...  The flat is merely adjacent to the left side of a note and sharp would be adjacent to the right side of the same key, but either way is a 1/2 step off.   "5, 4, 3, 2, 1 ~ 1, 2, 3, 4, 5"  From LEFT to RIGHT (so, no keyboard is needed for this kind of practice!): Left-hand: "5, 4, 3, 2, 1"  Right-hand "1, 2, 3, 4, 5"Left-hand: "5, 3, 1"  Right-hand "1, 3, 5", and such. So, you can have a fake-board the size of real keys or keyboard -- but remember that some electronic boards are shortened, not full piano size (they have fewer octaves -- fewer black and white keys).
Summary: Realize that chords generally consist of at least "three" notes/pitches/tones (Let's call them notes. Compare chords: notice C chord is exactly the same shape as F and G chords   Visualize the shape of the left hand for "C, F, and G" is all the same identical tri-formation.  Realize the situations where two ivory keys are together (adjacent, without a black one between them) -- so there the white key is the sharp -- or the flat (just 1/2 step to the "other" side) in some chords and scales. Flat a note in a similar way compared to sharping, but flatting is moving left (down) a half step in the flow of the music. Understand that the combination for a chord of three (or more) notes sounded together at certain distances between the notes ("intervals") are based on a pattern (or formula) for the chord in the "circle of notes" like find your "1st, 3rd, 5th" any or all of which may be off by half steps either way (sharped leftward or flatted rightward on the keyboard) to form various chords. Play the same chord on the right hand with the same kind of shape with the thumb and fingers again numbered left to right "1, 2, 3, 4, 5" but now starting from the thumb (1) to the right little finger (5); and though it looks opposite -- just ignore the thumb and finger switching, and so it is still the "same" kind of shaped tripod  Practice the numbering by "air piano" (on a table), moving your fingers while thinking: Get or (accurately) draw a partial or full-"model", paper keyboard to use, if you have no actual keyboard.

Making a crocheted cell phone case is much easier than it might seem. You just need a few things to do it. You will need:  Yarn in the color and type of your choice A crochet hook appropriate for the type of yarn you are using. Be sure to check the label of your yarn for recommendations on what size hook to use with the yarn. Scissors Button Needle and thread to wrap around your cell phone. You don’t need to worry about measuring your phone to get the right measurements for your cell phone case. All you need to do is to make a chain long enough to wrap around your cell phone width-wise.  The chain should be snug, but not super tight. If the chain is too tight, add a chain or two. If it is too loose, take a couple of chains out. Leave a long tail of about 10 to 12 inches (25 to 20 cm). You can use this yarn to sew the bottom closed after you finish making the case. Next, you will need to connect the beginning and end of the chain to begin crocheting in rounds. With the loop still on your hook from the last chain you crocheted, insert the crochet hook into the first link in your chain. Then, loop the yarn over the hook, and pull it through both stitches to secure them together. Your chain should now be connected in a circle. Once the chain is a circle, you can begin single crocheting around it. Start by inserting the hook into the first stitch in the round. Then, loop the yarn over and pull this yarn through the first loop. Loop the yarn over the hook again and then pull this yarn through both stitches on the hook. This will complete your first single crochet stitch.  Single crochet to the last stitch in the round, and then slipstitch to connect the first and last stitches. If you prefer to use a different type of stitch, then you can. For example, you could try the double crochet stitch, popcorn stitch, or cluster stitch. Be careful not to twist the stitches. You will need to continue to single crochet all rounds until the case is long enough to hold your cell phone. Once it looks like you are getting close, try slipping your cell phone into the case to see how far you have to go. Keep going until your entire cell phone fits in the case. . After you have achieved your desired length for the cell phone case, you will need to bind off your work. To do this, cut the free end of the yarn a few inches away from the hook, and then pull it out through your last loop to secure it. To deal with the tail, you can either weave in the end using a darning needle, or tie it in a second knot and cut the excess. Use the tail that you left at the beginning of making the case to sew the bottom of the case closed. If you did not leave a long enough tail, then tie a 10 to 12 inch (25 to 30 cm) piece of yarn to the tail and thread it through a darning needle. Then, stitch along the bottom of the cell phone case to close it.
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One-sentence summary --
Gather your tools and materials. Chain enough stitches Connect the chain with a slipstitch. Single crochet around the chain. Continue to single crochet all rounds. Bind off Sew the bottom closed.