WTB Sand, LED/T5; ?`s on chiller;

Lets get some baselines.

How old is the tank. has it cycled?
What are your parameters ( salinity (refractive index is best) ph, nitrate, nitrite ammonia and phosphates ca and kh we can worry about later if you don't have corals or anemones)

How much sand do you have in the DT now, (or is there) and what kind of sand is it? How much live rock?

As far as the chiller goes, what are your temps? Do you have/run an AC in the house? A chiller built by hand can be $40 up to $440 depending on how you want to do it. but I think this can be a separate topic al together.

If you can get a nice power head and have it agitate the surface water this will help to dissipate the head a little better in the tank. also in general more water movement means better overall stability in temperatures.

Lets start with the tank details and work down through your concerns.

 

All right, let's tackle what we can from top to bottom. I understand the idea that opinion be damned. As an engineer in multiple fields I tend to like fact and extrapolate data as needed rather than pull first thoughts out of the air myself. So I am in your boat.

A little background. I have been keeping FW fish for 25 years now, and Salties for 22. I have read a million book s throughout the years, and a billion posts since the millennial turn and common use of the internet. Long and short, I am not going to throw around opinion,or conjecture without letting you know that it is based on my experiences alone.

Chiller: Chillers that are hand made can be hard to pin down. It helps if you are going to build in something like a Johnson controller to regulate the on off temps of the system. Other than that you can make one for around $25 with a pump and a bucket. Cake walk. What I have ended up doing on a couple occasions is slide a length of tube down into (floor vents) the AC system and used a pump to circulate it that way.
Long and short, get yourself some 1/4 tubing and a 55-80 pump, drop the 3/8 nozzle down to a 1/4 threaded female and a male 1/4 threaded to quick connect. Connect ~25-50 feet of 1/4 tubing to the system and put the end of the line back into your tank/sump. Stick that length into your cooler. add water to the cooler with a cap full of bleach (at your own risk if you have kids/pets just keeps from it having to be cleaned constantly) add ice as needed. This is about the easiest cooling you can do for a chiller effect.

Water changes: So the Nitrates are a little on the upper end, but not terrible. A water change will help. I know I know. What is your water source, and what type of salt are you mixing? Your PH is closer to the lowersides than most would like to see. With that asked. Any ammonia is a sign of trouble. I am not going to lecture you on it, as you seem to have a handle on the cause of it from the snails, but any ammonia is a flag. nitrites similar to ammonia are trouble. now... back in the day before we had skimmers and refugiums and all this fancy stuff our indicator for a water change was nitrates. When your nitrates climbed, it was time for a change we had no way to get rid of them other than bailing out water and putting some back in. This was a weekly thing, that happened every Saturday morning at 8. It was religious. And many many people still stick to this like clockwork. Modern aquatic technologies have come a long way in letting us considerably change the way our tanks operate. That being said, a water change will have to happen... it just does. There will always come a point when one is needed. Your best bet to stretch that period is to add macro algae to reduce nitrates and phosphates in the water column, as well as a skimmer. So specifically to your situation, some good algae are needed to stretch that water change out as far as possible. As with any tank stocking levels, biofiltration performed by bacteria inhabiting your system will make a world of difference from tank to tank.

Tank size/Coral: the tanks a good size. Nice and stable and a great mid level tank. Got enough volume to handle some swings without complete meltdown. 200 lbs of rock is a bit much for the tank, but it wont be hurting anything so long as there is ample flow to move water around and through the rocks. With that being said. 200 lbs is a lot of rock... Like a lot... Typically for filtration purposes, you are looking at about an lbs per gallon. This is a pretty standard baseline that has been around since the mid 80's or so. With that being said I need to make the following disclaimer. There are a billion ways to set up a tank. And some tanks don't have any live rock for filtration. And that's cool. Its not right, its not wrong, it's just a different way to do it. I have no rock QT tanks. Regardless of opinion on rock need. the fact is that there are bacteria processing the nutrients in the water. That's how water is filtered in the system. This is known. We know this. We learned how to keep fish back in the 15th century. So with that out of the way. If you are keeping 200 lbs of rock in the system, be sure to keep an eye on dead spots for crap to settle. so long as you are not getting dead spots go with what you like.

As far as corals go. Corals are class Anthozoa of phylum Cnidaria and considered marine invertebrates. While many corals actively feed on many forms of nutrition by catching them with stinging cells, like anemones, the bulk of corals obtain energy provided by a symbiotic relationship with a unicellular algae that lives in the corals tissues, zooxanthella (symbiodinium in some regions) These particular corals tend to be easier to keep in systems without large amounts of changes needing to be made. Corallimorpharia, which is the extent order for mushrooms. In the hobby now-a-days its said that if you are killing mushrooms, then you are doing something very wrong. They are amazingly hardy and can survive very well in almost any tank.. I would start there if you are interested in corals, but it will not reduce your needs for water changes, or use the existing nutrients to cut them out of the system.

Sand beds: To merge a couple topics here. If your sand in the DT has been in there for 5 years. it's live sand. it is now living. it has been for 4.6 years or so now. I dont think the sand from the fuge is going to do any major sweeping changes to the sand in the main tank. It's just not likely that the main tank is not bacterially seeded after 5 years. Now to the business of sand... there is a lot of debate on this. has been for a good 15 years now. The facts are as follows. Imperically. we know that Deep sand beds work. anecdotally we know that Deep sand beds kill tanks. The reason we see die off with DSB's is people cannot keep their hands out of their tanks enough to let it work. The concepts of aerobic an anaerobic bacteria systems is very well known and is a system that has worked all over the world in nature to bring us literally to where we are today. With that being said. a Deep sand bed needs to be at a minimum of 4 inches, and a max of 8 in a 75. You can also look into a remote sand bed. This is a concept similar to a refugium but for sand. With that being said, a shallow sand bed is just as useful, and many many many people tout the effects of no bed at all and go bare bottom. Again a billion ways per tank.

Stock: Your stock levels are fine for a 75, and this will bring a huge amount of opinion and debate as well as to how much you can keep. So short and sweet, The more fish you have the more water changing you are going to be doing. Keep it low and you can stretch that out. I have a 75 with 9 fish in it. There is plenty of action to sit and watch. Your stocking list does concern me however. Wait on the Mandarin for a while. Let's get your tank under stable control before you start throwing such a difficult fish into the system. You could stand a little boost in your cleanup crew area with a couple more snails and a few more crabs, so keep an eye out for those when you can. I have never read that more fish makes a stable tank. I am not even sure I have heard that from anyone in fact. So I am not sure where that base is, but would be interested in it if whoever told you that has some ideas as to why.

Skimmer: A skimmer is 100% part of the filtration system. The skimmer was a marvelous invention to keep our tanks amazingly clean. the agitation of the bubbles works similar to the crashing of waves and ejection of sea foam on the shore. The bubbles help to bind up free floating proteins in the water column, and extrude them from the system. so how this is not part of filtration is beyond me. Seriously protein skimmers have been amazing. and occasionally when I change out my skimmer tanks I smile at all the wonderful disgusting goop that comes out because it saves me so much time. Seriously. They are amazing.

I am going to combine the vinegar thing in here. Go ahead and stay away from vinegar at this point. Your PH is already in question and adding an acid to the tank may cause some problems. You can alternatively use vodka with little to no side effects. The organic carbons in vodka will help the free floating bacteria and plankton in the water column bloom up real well, and the skimmer will pull those out more readily. You need to make sure your skimmer is up to snuff though. in a 75, start at 3 ml a day for the first week, and up to 4 ml for week 2-6 then 5 ml 6-12. its usually a short term thing to remove phosphates, however if you want to dose long term stick with 3 ml a day for... ever really. And be sure to empty your cup.

Lighting:Your lighting is plenty fine for fish only, and for most soft corals. those PC's are nice and old, and nice and hot. You could shift the bulbs to staggered. That is actinic, 50/50 in each to spread the spectrum around the tank a bit more, but that is just opinion. The heat from the PC's shouldn't be too bad for the tank, My 75 runs around 800 watts including halides. You should be just fine there.

Detritus/algae: To clarify, Detritus is a very specific term in biology. Detritus is non-living but organic particulate matter. That is, the poop of the poop eaters. so by definition the stuff growing is not detritus. It could be algae though. It could also be the little fan worms that grow on all rocks in tanks. Are they like little cork screws? You can try the tang, but based on the sound of it, I am not sure this is algae or maybe just rock stuffs that grows about. A pic or two would go a long way in helping there.

inverts; Have you tried something like a couple peppermint shrimp or the like? They are usually pretty easy to keep and will pick at just about anything to keep them going till the next feeding.

Tests: The API 'reef master' test kit has always left me wanting in the phosphate area, unless you REALLY have po4, it usually doesn't read well. but so long as your tests are still within expiration dates you should be alright. Your LFS should always run a water check for you. And I often bring one in just for sanity checks considering I live at mine.


Conclusion: The few red flags and questions I have are water source. Current TDS. really 200 lbs live rock? Tanks been running 5 years, sand in the DT is seeded, it just has to be. salt levels should be brought up to between 1.025-1.026/35 ppt. If you don't have a refractometer, then don't follow this advise you are probably fine. You could cause a die off just from the baseline of the hydrometer being off. Your temps are fine. I keep both my reefs mid day at around 78 in the summer and around 75 in the winter. So long as there are no 3+ degree swings during the day you should be fine in general with a stable temp in the 72-82 range.