I'm always running on low KH with modern reef Over multiple 4-part batches.. I can not for the life of me get a normal KH level. It just drops and drops while CA and MG are stable high. Rightnow im dosing 40% more of kh1 and kh2 just to keep ik level. Yes I calibrated my dosing pump. Yes the work well. Yes I checked.
I'm often hand dosing extra KH. I measured again this morning 5.9KH and dropping. I'm throwing in the towel and converting to something else. I have half a powder container AFR. At least that has a stable KH
edit: decided to try one last time so I ordered another new 4 part (my old one was almost empty) to see if this one is better. If this doesn't work I just can't recommend it to anyone. Its very expensive and so far, useless.
Hi :)
To help properly, we would need a bit more information about the complete setup:
- Aquarium volume
- How much RKS Reef Engine Core you dose per day from each part
- Whether you dose all four parts equally
- Current KH, calcium, magnesium, salinity, nutrients, and temperature
- Which test kits or devices you are using
- Whether you use an automated KH tester
- Whether you are dosing any nitrogen/nitrate source or other additives
- Whether you use calcium from any third-party product
- Whether you run phosphate absorbers, heavy metal absorbers, mixed chemical media, ozone, or continuous active carbon
- How the dosing containers are stored and how often they are refilled
Based on support cases we have seen before, this may be related to one of the following points. Without the information above, this is only general guidance and not a final diagnosis.
1. Dosing container setup/evaporation
If your dosing lines are connected directly to large canisters, or if the dosing containers are left filled for extended periods, evaporation may become a problem. Different liquids can evaporate or concentrate at different rates because their densities and compositions differ.
For best results, we recommend filling dosing containers with a maximum of around one month of use, keeping them closed, clearly labelled, and stored away from direct light. Transparent containers should also be kept away from strong aquarium lighting or room lighting.
2. Test accuracy / automated KH testers
If you are using an automated KH tester or any test kit, it is important to confirm that the result is accurate. Please validate the device or test kit with a known reference solution, such as Modern Reef Precision, or another reliable reference standard.
Sometimes the issue is not the dosing system itself, but an incorrect reading or a device that needs calibration or maintenance.
3. Calcium level or additional calcium sources
Please do not dose a third-party calcium source together with the system unless there is a clear reason. If calcium is between
390–420 ppm, it is already in a good range. Do not increase calcium only because you prefer a specific higher number.
Our Proportional Consumption Reef Engine Core RKS is designed to work by proportional consumption. If KH, calcium, magnesium, salinity, nutrients, temperature, and coral response are all in range, stability is more important than chasing one exact number.
In some cases, users report calcium increasing, and the cause is not immediately obvious. Possible reasons can include test error, additional calcium sources, or system-specific factors. Also, please double-check calcium test accuracy. Some calcium tests can give misleading results if not used exactly correctly. For example, Hanna Calcium.
4. Cold temperature / solid particles in KH1 or KH2
If you live in a cold area, check
KH1 and KH2 carefully. During cold storage or shipping, visible solid particles can sometimes appear. This does not automatically mean the product is damaged.
If you see solid particles:
- Keep the cap closed.
- Place the bottle in hot tap water for about 30 minutes.
- Gently mix the bottle.
- Check that the particles have dissolved back into the solution.
- Let the liquid return to room temperature before dosing or calibrating the dosing pump.
Do not use boiling water, do not microwave the product, and do not open the cap while warming.
Also, try to keep the dosing containers at a stable temperature, ideally similar to the aquarium area. For example, if the aquarium is in the living room but the canisters are stored behind the wall in a cold garage, the temperature difference can affect the liquid and even dosing pump calibration accuracy.
5. Dosing pump calibration
Please make sure each dosing pump head is calibrated with the same liquid it will dose. Do not calibrate with RO/DI water and then dose Reef Engine Core, because different liquids can move through dosing tubes at slightly different rates.
For best accuracy:
- Calibrate KH1 with KH1
- Calibrate CAL with CAL
- Calibrate KH2 with KH2
- Calibrate MAG with MAG
- Use the same tubing length as in the final setup
- Recalibrate regularly
6. Dosing order and timing
A dosing pump is recommended. Ideally use a 4-head dosing pump and dose in this order:
- KH1
- CAL
- KH2
- MAG
Leave
10–15 minutes between each part and dose into a high-flow area of the sump. If there is no sump, dose into a strong-flow area of the aquarium, away from corals and low-flow zones.
Do not dose all parts at the exact same time.
7. Chemical filtration and extra additives
For best results, avoid unnecessary use of:
- Phosphate absorbers
- Heavy metal absorbers
- Mixed chemical absorbers
- Ozone
- Continuous active carbon
- Strong chemical filtration media without a clear reason
These can remove or reduce some supportive components in the formula and may interfere with the balanced proportional method.
In normal use, you also do not need extra trace blends, amino acids, color boosters, growth boosters, or random additives. Too many extra products can create instability or accumulation.
8. Temporary 2-by-2 balance method
If all the above points are checked and everything seems correct, you can temporarily use the system with the
2-by-2 balance method.
This means:
- KH1 and KH2 are dosed at the same amount
- CAL and MAG are dosed at the same amount
- The KH1/KH2 pair and CAL/MAG pair may be adjusted separately for a limited period
Example:
- KH1: 10 ml per day
- KH2: 10 ml per day
- CAL: 8 ml per day
- MAG: 8 ml per day
This can be useful during the early stage of a reef aquarium or when biological activity and nitrogen cycling affect KH behaviour. Once the aquarium becomes more stable, the system should usually return to equal dosing of all four parts.
That is also why the system is structured in pairs:
Base KH1 and Base KH2, and
Base CAL and Base MAG. Some aquariums may need to start this way to reach balance, and after some time the system often stabilises and can return to equal-part dosing.
Please also read the complete RKS Reef Engine Core 7.7x Method Guide here:
https://modernreef.eu/rks-reef-engine-core-7-7x-complete-method-guide/
And if you want direct help, you are always welcome to contact our 24/7 WhatsApp support:
+49 175 9627777
