I believe there is a EXCEL program for pump volume and velocity in relation to static head and friction loss. If not I can post the URL. I do not know if Joshi will allow the posting of the program on other sites but his site has a download available, you just need to have Microsoft Excel with the problem solver option loaded on your computer. I know of no posted program for bulkhead flow. I can not fathom anyone ever trying to write such a program because of the huge variance that even small variables would make. glass-holes.com is the only site I know that tests its overflow rates through back wall bulkheads. They use both flow meters and they measure by the time bucket loads also for verification. Wetwebmedia.com repeatedly states what they find to be the expected and average flow rates of different sized bulkhead overflows through standpipes., and I have no reason to doubt Bob Fenner or Anthony Calfro. No where will you find measured flows that are as high as stated by tank manufacturers for "reef ready" tanks. Sand bed calculators can be easily found. Again I can only give an URL, I can not post someone Else's program on this site. I could easily write a basic math plug and chug formula for this as it is entirely based on cubic inches and the specific volume of different sands in units of cubic inches and Drs. Foster and Smith give the number of cubic inches per bag of sand for the different types of sand. It also helps to know the weights of the different sands which they will give out over the phone. Example for a 120 gallon tanks 4 inch deep sand bed. (24) inches x (48) inches x (4) inches = 4608 cubic inches, oolitic sand is 320 cubic inches to the bag, and each bag weighs 20 pounds ( (4608 / 320) x 20 lbs)= 288 pounds, which would be rounded up to 300 pounds or 15 twenty pound bags of sugar sand size oolitic aragonite. I will submit some formula write ups to the super moderator and if he approves them they will be posted. I will also submit some urls to him along with there descriptions and let him decide how they should be posted. Right now he is in the middle of setting up categories that are more specific so I expect he will want URL's to be submitted to specific areas and not just a broken down lit of URL's.
The hexagonal volume calculator was a nice touch. I haven't seen that before even on scientific sites, but I can not remember ever needing the formula yet alone a visual basic program for it. It is nice for those few with a hex tank though.
Most the programs I use come from science people so are usually EXCEL as that is a widely used piece of software that is very versatile and requires less actual programming, but provides none of the pretty graphic shell.