Ninjoma

I think they are roots from baby Java ferns.

Could be roots, could be staghorn algae, could be black beard algae or it could be something else. Pictures would help.

Nitrates are the primary nutrient you test for. If you are dosing easy green and your nitrates are 20+ppm, you generally have enough nutrients. The other way to tell if your tank lacks nutrients is when you notice your plants are showing signs of nutrient deficiency. This article has a helpful breakdown of the different nutrient deficiency symptoms https://www.aquariumcoop.com/blogs/aquarium/plant-nutrient-deficiencies

I have both and I prefer the german blues. They are much more vibrant and colorful. They are both sorta bossy, but german blues are smaller so it's less worrisome. Bolivian rams work in more setups though.

I have a pair of bolivian rams with my roseline sharks, SAEs, pearl gourami and a rainbow shark. They seem to more or less ignore all the other fish, but will occasionally chase eachother. I also saw one fight with one of my dwarf crayfish. I also have a pair of german blue rams with an angelfish, honey gourami and platies. They like to chase eachother and the platys. Rams seems pretty anti social in my experience.

I keep mine around 72-75 and they have been doing great.

I would just keep them. They'll help clean the tank and their population will control itself once the tank achieves balance. I find it way more stressful to try removing every pest snail, then just having extra snails in the tank. If you do want to remove them, loaches have a reputation for being good snail hunters, so I would consider dwarf chain loaches. I haven't had the opportunity to keep yet, but I have tried assassin snails and they were too slow for my taste.

You definitely can add easy iron if you think extra Iron is needed, I would just be careful because you are likely to have a hair algae outbreak if there is too much unused Iron in the tank.

Yeah, easy green will add enough iron. I wouldn't add any extra iron for val or dwarf sag. Root tabs would help them though.

Maybe a pearl gourami or kribensis? An angelfish might work too, but it might get too big long-term.

Since the leaves are turning yellow, I would guess it is a nutrient deficiency like phosphates and/or potassium. I would personally start doing more frequent and/or larger water changes to get the nitrates lower so you can dose more easy green and see if that helps.

I've run into algae that looks like this a few times. I think it's staghorn algae. Lowering light intensity and/or duration would help. You can also try using easy carbon, ideally applying it directly to the algae using a pipette. Adding some animals to eat it would also help. For your tank size, more amano shrimp would probably be the best bet.

Hmm, it could be a nutrient deficiency then. This article may help you determine which kind https://www.aquariumcoop.com/blogs/aquarium/plant-nutrient-deficiencies. What are your nitrates at?

Is the tank or the substrate relatively new? If so it could be brown diatom algae. You can either wait it out and it will go away on its own or you can add something like otos that will eat it. Edit: also are the rhizomes above the substrate?

I haven't used these stands, but I remember seeing this thread recently and they came up.

My crabs are getting settled. I'm really enjoying them so far. I caught my first mating dance today!

I think you could do a lot more than 10 in 75g if the only other animals in the tank are neos and guppies. I would get at least 20 personally.

Since you also have a sponge filter, you could just discontinue using the HOB since it has been causing you so many issues.

If you are interested in getting them I think it's worth it just for the animals' sake. I wouldn't consider this a waste of time or money at all.

I think changing some water is a good idea regardless of what your nitrates test at because your tank is likely creating excess of something that you aren't testing for or is becoming deficient in something you aren't testing for. I will sometimes test my water before I do water changes to try to hit my target nitrate level. More often I just change 25%-50% depending on what I feel up to.

It's more like, you want to make sure there are enough nutrients available in the tank at first. Then you want to sustain that level of nutrients

If it's 1.5g, yes 3 drops per week will help your plants. Personally I would test for nitrates every day. If they are below 20ppm I would add 2 drop per gallon every day. Once your nitrates are above 20ppm, I would go with the normal dose of 2 drops per gallon per week.

I would add some easy green. How many gallons is the tank? ACO recommends 1 pump per 10g or two drops per 1g. I would add one or two doses and then test your nitrates a few hours later. You want to get to about 20-50ppm nitrates from dosing easy green.

If the temperature of your water is 72-78 degrees without a heater, then a heater isn't a must for most fish and plants. If the temperature of your water is 71 degrees or lower without a heater, it's probably a good idea to have a heater for most fish. Different fish and plants require different temperature ranges, so you may need to look at the care requirements for the particular animals and plants you want to include in order to tell if a heater is a must for you or not. That's not technically true, but it's good advice for most people. The advice I've heard from ACO is having an air stone in your tank can prevent a lot of potential problems and if you are using an airstone, you might as well connect the airpump to a sponge filter.

Another option to consider is a 65g tank. It is the same footprint as the 40breeder, but taller.