Fish Are Dying Again

[Queen Bee]

The last 2 weeks I have lost 3 platy, 2 guppies, 2 otto, 1 cory.

It is a 29 gallon been running since October. No live plants except for some java moss. I've been doing the weekly 25% water changes and the tests have all looked good. Ammonia, nitrite at 0, ph at 8 and nitrate at 40. At first I thought that the new red eye lyretail sword was killing the fish. He always seemed to be picking on the fish and chasing them and biting. I returned him to the store a few days ago (Got no credit at all, not too happy about that). After returning him was when the cory and 1 of the platy died.

Thought the cory was hiding, didn't see for a couple of days. Sifted through the tank and found it dead. I tested the water and the nitrate was at 80. (Weekly water change was done 3 days before this) Did a water change and couple of hours later it was back at 20. Could the cory being dead for a couple of days have caused the rise in nitrates or do I have something else going on?

Tank is still below the recommended stocking level.

I have lowered the heat, (noticed the platy hanging out at surface, but not gulping) and turned up the airstone for more agitation. Heat was a little too high as the apartment gets extreamly cold most of the time. It was at 80, lowered it to 76 over the last couple of days.

Used test strips to measure the alkalinity. It was reading 0 - 50 hard to tell. I used to run crushed coral in the tanks and removed it after running it in the tank for 6 weeks. Water was tested at the lfs and he said that we have no buffers in our tap water. That was causing the water to become very acidic. I pulled the coral out because I wanted to get gourami and the ph was too high for them. Do I need to put it back in and keep it in?? I guess from the water changes I've done since then might have removed the buffers the coral put in the water. I kept an eye on the ph, and it hasn't changed at all since I removed it. It is at a constant 8

Anything you think I over looked? Should these steps settle the tank back down. Lost 2 tanks full of fish this past summer and don't want to go there again.

 

[Miss Wiggle]

could be that the new swordie bought in a disease, did you quarantine him before adding him to the tank, any symptoms on the fish?

 

[Queen Bee]

could be that the new swordie bought in a disease, did you quarantine him before adding him to the tank, any symptoms on the fish?

fish was quarantined in separate tank for a week. He showed no of illness. All fish remaining in the tank appear healthy, no scratching, no spots. Even the gourami's that are very prone to getting sick appear fine.

Platy that is still alive that was hanging out at surface is swimming in all levels of the tank this morning.

 

[rdd1952]

The dead fish definitely could have caused a rise in nitrate as there wold have been more ammonia from the decaing fish.

As you mention, your pH is a high for most of the fish you are keeping. While most fish can adapt to a pH that's outside their optimal range, if there is something in the tank that causes stress, it can have a quicker effect on them. I would leave the coral out and let the pH level out (what is the tap pH?). With no buffers, I'm surprised it would be as a high as 8. That's definitely not acidic but pretty high alkaline. The fish you have would prefer the acidic water. As long as it doesn't drop into the 5s, you won't have a problem with acidic water. My 29 gallon runs in the low 6s as I have 0 GH & KH.

 

[Queen Bee]

The dead fish definitely could have caused a rise in nitrate as there wold have been more ammonia from the decaing fish.

As you mention, your pH is a high for most of the fish you are keeping. While most fish can adapt to a pH that's outside their optimal range, if there is something in the tank that causes stress, it can have a quicker effect on them. I would leave the coral out and let the pH level out (what is the tap pH?). With no buffers, I'm surprised it would be as a high as 8. That's definitely not acidic but pretty high alkaline. The fish you have would prefer the acidic water. As long as it doesn't drop into the 5s, you won't have a problem with acidic water. My 29 gallon runs in the low 6s as I have 0 GH & KH.

The tap water is reading at 7.4. In the initial tank that had no coral the ph dropped to 6, maybe lower, but the test kit only went as low as 6. This tank was reading 6.8 when I first put the coral in (oct 4) I took it out (nov 17) the ph read 8 and hasn't changed since then. I thought taking it out would lower the ph, but it did nothing. Fish seem to have adapted to the ph.

 

[rdd1952]

The reason it hasn't changed is that the coral has buffered the water up. Since you removed it though, every water change should bring it down some as you are replacing buffered water with your tap water. Have you added anything else to the tank (rocks, decorations, etc.) in that time frame that could be buffering it? It really sounds like there is something else in the tank that is buffering it up. How did you have the coral in the tank and are you certain you removed all of it?

It sounds as if your tank may be overstocked, thus producing the high nitrate readings. Lack of live plants means that all ammonia eventually becomes nitrate (1 ppm of ammonia is 3.7 ppm of nitrate). High nitrates will push the pH down too so that I probably the reason your pH was dropping so low. You may need to step up the size/frequency of your water changes to try to keep the nitrates below 20. While they aren't harmful at levels up to 100 and above, high nitrates can lead to other problems such as algae and as mentioned, low pH.

 

[drobbyb]

I agree with Rdd. A high fish load will definately cause your pH to plummet. More waterchanges and lowering the number of fish in the tank should help you get that tank under control. How much water are you changing and how often?

Edit: I run crushed coral in my filters. I have to change my water every week of at least 50%. Crushed coral takes time to work it's magic. It slowly builds up in your tank over time increasing your KH and pH. If you don't change your water often enough, you will run into problems with pH shock with every waterchange. It's quite easy to kill fish this way. You must stay on top of your waterchanges in order to prevent this. After all we aren't trying to raise the KH, we are preventing a pH crash.

 

[Queen Bee]

I had the coral in a fine net bag tied very tightly. Certain none of it remained in the tank. I've never had more than 14 fish in the 29 G tank, most of which were just at the inch marker some a little smaller.

I do have algae problems and the otto has been working at it for the last couple of weeks.

I added a piece of rock that looks like a log sometime before Christmas (probably Nov). They tested it at the store, and said it wouldn't effect the ph. They called it dragon lace, or something like that.

Nitrate has never read above 40 except after the death of the cory. Usually I test it before I do the water changes (25% once a week, topped up midweek). Afterwards it goes down to 10 - 20

The tank that had the constant downswing of ph was the one that crashed last summer. the nitrate readings during that time were 0 - 5, as I never got it to cycle.

 

[rdd1952]

I've never heard of dragon lace and couldn't find anything with a Google search either. Since you added it in November, I strongly suspect it is what's keeping your pH up. Simplest way to check is take it out and put a couple drops of vinegar on it. If it fizzes, then it's raising your pH.

I did find this lace rock however. It doesn't say that it buffers the water and raises the pH but the fact that is says "perfect for cichlid tanks" would almost lead me to believe it does but it says it's made of a poly-resin which is generally inert.

 

[Queen Bee]

I've never heard of dragon lace and couldn't find anything with a Google search either. Since you added it in November, I strongly suspect it is what's keeping your pH up. Simplest way to check is take it out and put a couple drops of vinegar on it. If it fizzes, then it's raising your pH.

I did find this lace rock however. It doesn't say that it buffers the water and raises the pH but the fact that is says "perfect for cichlid tanks" would almost lead me to believe it does but it says it's made of a poly-resin which is generally inert.

That does look like the piece I put in the tank. Since the store tested it, i never thought of testing it again myself.