Colombian Ramshorn Apple Snail Healthy?

My giant ramshorn (Marisa cornuarietis) has been acting funny recently- doing a lot of resting on the ground in his shell when hes normally up at the top and active. I've also noticed his shell looks different and not sure if it's something to do with my water.
I can't copy and paste the sick fish thing sonill put what I can remember.

It's a 55gal tank
Has two filters, an aquatech 30 -60 & a sunsun hw 302 canister filter
Not heated but stays at about 77-79, we try to keep it at 74 but it's so hot in my state that the ac can't get the house below 77.
I vacuum both water and the substrate
50% water changes with prime every friday
Tanks fully cycled, has been since January

Ammonia -0
Nitrite - 0
Nitrate - 40
Ph -6 (just added some ph up, slowly trying to get it to 7. Idk why it's so low in my tanks, my tap water is 7)

He eats fresh zucchini, yellow squash, and whatever food falls to the bottom. Which are:
FD brine shrimp, frozen blood worms, wardley shrimp pellets, apI shrimp pellets, aqueon tropical flakes, hikarI micro pellets, new life spectrum thera a.

Hes housed with 14 neon tetras, 5 cory cats, 1 honey gourami. All tank mates are acting fine.

I only just started noticing him act weird in the last 2 weeks. No other symptoms beyond the shell and behavior.

Attached are photos of him now (one with zucchini] and one from when we first got him in april.
Also attaching photo of the tank

 

Couldn't get the tank photo to add so posting it separate

 

Ramshorn can cope with that temperature but you ph is not good at all your water is coming out neutral 7 and that's bottom line it needs adjusting 7-7.8 and get anything rich in minerals for him to eat, take the centre and seeds out of the zucchinI they won't eat that and it will foul your water, hes not looking to good the low ph as taken its toll on the shell

 

Ramshorn can cope with that temperature but you ph is not good at all your water is coming out neutral 7 and that's bottom line it needs adjusting 7-7.8 and get anything rich in minerals for him to eat, take the centre and seeds out of the zucchinI they won't eat that and it will foul your water, hes not looking to good the low ph as taken its toll on the shell

thank you, I hadn't realized it was so low bc I'm bad at checking my ph. check everything else but not my ph, and that's on me. I'm slowly getting the ph back up but can only adjust it so much in one day bc I don't want to put them into shock.
ill do another .2 tomorrow (I put it up from 6.2 {I misread the thing} to 6.4 and ill repeat this until its 7.5

all of my tanks are dropping in ph and idk why, they don't share a substrate, rocks, etc and I do water changes every week, so I'm not sure what's making it drop

 

Ramshorn can cope with that temperature but you ph is not good at all your water is coming out neutral 7 and that's bottom line it needs adjusting 7-7.8 and get anything rich in minerals for him to eat, take the centre and seeds out of the zucchinI they won't eat that and it will foul your water, hes not looking to good the low ph as taken its toll on the shell

what would you suggest I get/do? I defintiely don't want him to die, hes by far my favorite creature in the tank. is there something you know of that I can get him to help him now?

 

Theres is a way if you want and that's take what you can out of the tank and put in a bucket with air stone then raise the ph in the tank in one go, you will then have to drip the snails over 5hrs slowly to acclimatise them to the tank water, I have had shrimpers do this when the gh/kh are very low with success but have never guided anyone with snails, doing it the way you are is best under the circumstances and can only be good even if it is in small increments

 

Theres is a way if you want and that's take what you can out of the tank and put in a bucket with air stone then raise the ph in the tank in one go, you will then have to drip the snails over 5hrs slowly to acclimatise them to the tank water, I have had shrimpers do this when the gh/kh are very low with success but have never guided anyone with snails, doing it the way you are is best under the circumstances and can only be good even if it is in small increments

Thank you. I'm also going to get some crushed coral and add a bit to my canister filter so that itll raise it and keep it more steady over the long run

 

It may be worth you looking a seachem equilibrium to give you some stability