Don't want to be that guy, but whatever. Couple of things: seems like you are putting waaayy to much "bad" stuff in the tank already just to get it to cycle - most people cycle with a small amount of food or something like that. At the rate you are going, with the look of the tank, pumps, and the wet/dry, once the cycle is over you are going to need to do multiple 80% water changes (obviously an exaggeration, but still). You are starting a new build START A NEW BUILD!, haha, but seriously you are going to have soooo many problems down the line if you use all of this dirty stuff. Its crazy to use dirty algae ridden stuff to cycle a new tank (filter sock). My advice is to clean everything - the key to this whole thing is starting right and not introducing nuisances into the system. The tank that is pictured above was started with a new 29g tank from petco that I cleaned so much I would have eaten out of it, 30lbs of unopened live sand, bleached liverock, two 1/5lb pieces of live rock from a 5g nano I had and a thick piece of coralline algae from my LFS that I dipped in Coral RX. That's it, not used filter sock or old live rock/sand or anything. Did it take long to cycle? Hell ya, but when it was cycled everything was in range and I haven't had a single algae issue to date for 4 years (knock on wood
). Maybe most people do have that much algae when they cycle a tank, I dunno, I didn't. That picture is a week after the tank cycled and I didn't lose any of those fish - not one smidgen of algae.
I have had my own issues don't get me wrong, but this is what I would do in your situation.
1. If you haven't already, which it doesn't look like you have (no offense), give the tank a good hard cleaning with salt water, a rough sponge and a razor blade. Dry it out completely and go over it again with RO water and clean paper towel. Hopefully you can save the water that's already in the tank.
2. Bleach or acid wash the rock/sand, this will take a week or two, google search cooking live/dry rock or bleaching live dry/rock. (Bulk Reef Supply Pukani rocks sometimes needs to be bleached/acid washed or cycled for phosphate removal so you will find a ton of threads on it). There is no way I would ever use old sand, who knows how much phosphate it could leak into your tank...even bleaching it wont help that. Then what? Have to buy a GFO reactor or something similar to get it out? For sure not.
3. Clean your equipment in some vinegar for a day or so.
4. Just my opinion, but convert that wet/dry into a refugium/sump. I am in the camp that thinks the technology is outdated and just causes issues down the road (many people refer to it as a nitrate factory). I run a bare bottom tank so I have a deep sand bed and macro algae in my sump, but it seems as if people are starting to move towards not keeping anything but equipment in one. Cheapest way to do this is buy a 20g long tank from petco or find one on Craigslist.
4.Get an RO/DI, could be the best piece of equipment I have - you can find some cheap knock offs and then just buy good filters from filter guys to save money.
5.Patience. Nothing happens fast in this hobby. The more time to take now, you will get back 100 fold later when you don't have issues.
Good luck, let me know if you have questions. I am excited to follow your progress. Try and think clean, clean, clean.
And this is just one person's opinion. You ask 100 people, you'll get 100 different answers.
You said hang on the back filter, did you mean overflow? If so, I have used one in the past, they get annoying but they do the job. Make sure to watch some youtube clips on what can happen if the power goes out, ext.
