Ph Problem In My 36 Gallon

[Bunchbro84]

My 36 gallon bowfront has had many problems in the past, but now seems to have one persistent problem, ph. The ph is around 8.4 and I don't have the slightest idea why. Tap water (from the well) is around 7.6 and I had just recently tried my luck with otos. I added 2 otos on Saturday but they died shortly after. I also added 3 glowlights to company the 1 that was not dead, but 1 has died and another is not looking good. I have tried driftwood, but it didn't seem to help. I have soaked and boiled it and I don't think  there are any tannins left. My question is, why is the ph so high. I do have plants in there, and the parameters are ammonia 0  Nitrite 0 and nitrates around 20 more or less. I need the ph to be 7 for a community tropical aquarium, and it is very upsetting to keep losing these fish.

 

[sawickib]

Hmmmm, so your tank is cycled right? Whats inside the tank? i.e. substrate and decor
 
The otos need a established tank, i mean this by they need lots of grazing algae, so youll want  to wait about 6 months plus for nice amounts of green algae.
 
Sorry about your losses I hope we figure this out for you.

 

[McCool]

Substrate? Do you have any decorative rocks? I would take a cup of tap water and leave it out for 24 hours and then test it. you can also take a cup of tap and put some of the tank substrate it, then test that and see If it has changed.

 

[Bunchbro84]

the tank is cycled and the substrate is just gravel. Ornaments are generic resin ornaments.

 

[McCool]

Hmmm. I'm honestly not sure then. I would test the gravel and left out tap just to make sure, but I'm sure someone else will chime in with ideas.

 

[BerryAttack]

the decor can be causing the issues as the paint leaches into the water. did you just buy them and think they would look nice in the tank? sometimes the brand at the pet store are not safe and some are. 
if you are already testing the water before adding it in - which is fine and then it is changing it is probably the decor you have. 
take out all the decor, do a 90% water change with treated water.. allow your tank to fully cycle. then in each bucket or container put each decor piece in each out with the water that you are using for the tank (don't need to treat) then allow them to sit for a week then test each one. (you don't need to test the wood as it should be fine) 
then when you test each decor item you'll find your issue. that is my guess. good luck.
 
neons and otos need a very mature tank that has run successfully for 6 month before adding it in. algae is one factor, but try to by the ones that have not been caught in the wild as the wild ones will die almost instantly. and these fish are more for live planted tanks. get a bristle nose pleco if you wish to have something of a sucker fish and or a rubber lip pleco as they are smaller then the bristle nose.